diff --git a/module/core/process_tools/src/process.rs b/module/core/process_tools/src/process.rs
index 98027c9f7a..f41e3bf120 100644
--- a/module/core/process_tools/src/process.rs
+++ b/module/core/process_tools/src/process.rs
@@ -176,6 +176,22 @@ pub( crate ) mod private
 
     report.out = out;
 
+    let err = String::from_utf8( output.stderr )
+    .context( "Found invalid UTF-8" )
+    .map_err( | e |
+      {
+        report.error = Err( e.into() );
+        Err::< (), () >( () )
+      });
+
+    if err.is_err()
+    {
+      return Err( report );
+    }
+    let err = err.unwrap();
+
+    report.err = err;
+
     if output.status.success()
     {
       Ok( report )
diff --git a/module/move/willbe/src/action/mod.rs b/module/move/willbe/src/action/mod.rs
index 08c634878f..03d817fc44 100644
--- a/module/move/willbe/src/action/mod.rs
+++ b/module/move/willbe/src/action/mod.rs
@@ -8,6 +8,8 @@ crate::mod_interface!
   layer main_header;
   /// Publish packages.
   layer publish;
+  /// Return the differences between a local and remote package versions.
+  layer publish_diff;
   /// Generates health table in main Readme.md file of workspace.
   // aaa : for Petro : give high quality explanations
   // aaa : add more details to description
diff --git a/module/move/willbe/src/action/publish_diff.rs b/module/move/willbe/src/action/publish_diff.rs
new file mode 100644
index 0000000000..d8f648aba7
--- /dev/null
+++ b/module/move/willbe/src/action/publish_diff.rs
@@ -0,0 +1,38 @@
+/// Internal namespace.
+mod private
+{
+  use crate::*;
+
+  use std::path::PathBuf;
+  use crates_tools::CrateArchive;
+
+  use _path::AbsolutePath;
+  use wtools::error::for_app::Result;
+  use diff::{ DiffReport, crate_diff };
+
+  /// Return the differences between a local and remote package versions.
+  #[ cfg_attr( feature = "tracing", tracing::instrument ) ]
+  pub fn publish_diff( path : PathBuf ) -> Result< DiffReport >
+  {
+    let path = AbsolutePath::try_from( path )?;
+    let dir = CrateDir::try_from( path )?;
+
+    let package = package::Package::try_from( dir.clone() )?;
+    let name = &package.name()?;
+    let version = &package.version()?;
+
+    _ = cargo::pack( cargo::PackOptions::former().path( dir.as_ref() ).dry( false ).form() )?;
+    let l = CrateArchive::read( packed_crate::local_path( name, version, dir )? )?;
+    let r = CrateArchive::download_crates_io( name, version ).unwrap();
+
+    Ok( crate_diff( &l, &r ) )
+  }
+}
+
+//
+
+crate::mod_interface!
+{
+  /// Publishes the difference between the local and published versions of a package.
+  orphan use publish_diff;
+}
diff --git a/module/move/willbe/src/command/mod.rs b/module/move/willbe/src/command/mod.rs
index 08cf29ba2a..384d1540f4 100644
--- a/module/move/willbe/src/command/mod.rs
+++ b/module/move/willbe/src/command/mod.rs
@@ -34,6 +34,17 @@ pub( crate ) mod private
       .routine( command::publish )
       .end()
 
+    .command( "publish.diff" )
+      .hint( "Display the differences between a local and remote package versions." )
+      .long_hint( "Following this command, you will immediately get a comparison between the local and remote packages. It looks at each file, identifying those added, removed, or modified. A full report will then be generated where you can quickly and easily see the differences." )
+      .subject()
+        .hint( "Provide path to the package that you want to check.\n\t  The path should point to a directory that contains a `Cargo.toml` file." )
+        .kind( Type::Path )
+        .optional( true )
+        .end()
+      .routine( command::publish_diff )
+      .end()
+
     .command( "list" )
       .hint( "list packages from a directory" )
       .long_hint( "generates a list of packages based on the provided directory path. The directory must contain a `Cargo.toml` file." )
@@ -237,6 +248,8 @@ crate::mod_interface!
   layer list;
   /// Publish packages.
   layer publish;
+  /// Used to compare local and published versions of a specific package.
+  layer publish_diff;
   /// Generates health table in main Readme.md file of workspace.
   // aaa : for Petro : what a table??
   // aaa : add more details to documentation
diff --git a/module/move/willbe/src/command/publish_diff.rs b/module/move/willbe/src/command/publish_diff.rs
new file mode 100644
index 0000000000..baedd83605
--- /dev/null
+++ b/module/move/willbe/src/command/publish_diff.rs
@@ -0,0 +1,39 @@
+mod private
+{
+  use crate::*;
+
+  use std::path::PathBuf;
+  use wca::Args;
+
+  use wtools::error::Result;
+
+  /// Command to display the differences between a local and remote package versions.
+  ///
+  /// # Arguments
+  ///
+  /// * `args` - Command line arguments.
+  ///
+  /// # Returns
+  ///
+  /// Returns a `Result` indicating success or failure.
+  ///
+  /// # Errors
+  ///
+  /// Returns an error if there is an issue with the command.
+  pub fn publish_diff( args : Args ) -> Result< () >
+  {
+    let path : PathBuf = args.get_owned( 0 ).unwrap_or( std::env::current_dir()? );
+
+    println!( "{}", action::publish_diff( path )? );
+
+    Ok( () )
+  }
+}
+
+//
+
+crate::mod_interface!
+{
+  /// Publishes the difference between the local and published versions of a package.
+  orphan use publish_diff;
+}
diff --git a/module/move/willbe/src/entity/diff.rs b/module/move/willbe/src/entity/diff.rs
new file mode 100644
index 0000000000..27c39543ff
--- /dev/null
+++ b/module/move/willbe/src/entity/diff.rs
@@ -0,0 +1,113 @@
+mod private
+{
+  use crate::*;
+
+  use std::
+  {
+    collections::HashSet,
+    fmt::Formatter,
+    path::PathBuf,
+  };
+  use colored::Colorize;
+  use crates_tools::CrateArchive;
+
+  use wtools::iter::Itertools;
+
+  /// The `Diff` enum is designed to represent differences between two versions
+  /// of some kind of item identified.
+  #[ derive( Debug ) ]
+  pub enum Diff< T >
+  {
+    /// This variant represents items that are identical or same in both versions.
+    Same( T ),
+    /// This variant represents items that exists in both versions but have been modified.
+    Modified( T ),
+    /// This variant represents items that were added.
+    Add( T ),
+    /// This variant represents items that were removed.
+    Rem( T ),
+  }
+
+  /// The `DiffReport` struct represents a diff report containing a list of `Diff` objects.
+  #[ derive( Debug, Default ) ]
+  pub struct DiffReport( Vec< Diff< PathBuf > > );
+
+  impl std::fmt::Display for DiffReport
+  {
+    fn fmt( &self, f : &mut Formatter< '_ > ) -> std::fmt::Result
+    {
+      for diff in self.0.iter()
+      .sorted_by_key( | d | match d { Diff::Modified( df ) | Diff::Same( df ) | Diff::Rem( df ) | Diff::Add( df ) => df } )
+      {
+        match diff
+        {
+          Diff::Same( t ) => writeln!( f, "{}", t.display() )?,
+          Diff::Modified( t ) => writeln!( f, "~ {}", t.to_string_lossy().yellow() )?,
+          Diff::Add( t ) => writeln!( f, "+ {}", t.to_string_lossy().green() )?,
+          Diff::Rem( t ) => writeln!( f, "- {}", t.to_string_lossy().red() )?,
+        };
+      }
+
+      Ok( () )
+    }
+  }
+
+  /// Compare two crate archives and create a difference report.
+  ///
+  /// # Arguments
+  ///
+  /// * `left` - A reference to the left crate archive.
+  /// * `right` - A reference to the right crate archive.
+  ///
+  /// # Returns
+  ///
+  /// A `DiffReport` struct representing the difference between the two crate archives.
+  pub fn crate_diff( left : &CrateArchive, right : &CrateArchive ) -> DiffReport
+  {
+    let mut report = DiffReport::default();
+
+    let local_package_files : HashSet< _ > = left.list().into_iter().collect();
+    let remote_package_files : HashSet< _ > = right.list().into_iter().collect();
+
+    let local_only = local_package_files.difference( &remote_package_files );
+    let remote_only = remote_package_files.difference( &local_package_files );
+    let both = local_package_files.intersection( &remote_package_files );
+
+    for &path in local_only
+    {
+      report.0.push( Diff::Add( path.to_path_buf() ) );
+    }
+
+    for &path in remote_only
+    {
+      report.0.push( Diff::Rem( path.to_path_buf() ) );
+    }
+
+    for &path in both
+    {
+      // unwraps are safe because the paths to the files was compared previously
+      let local = left.content_bytes( path ).unwrap();
+      let remote = right.content_bytes( path ).unwrap();
+
+      if local == remote
+      {
+        report.0.push( Diff::Same( path.to_path_buf() ) );
+      }
+      else
+      {
+        report.0.push( Diff::Modified( path.to_path_buf() ) );
+      }
+    }
+
+    report
+  }
+}
+
+//
+
+crate::mod_interface!
+{
+  protected use Diff;
+  protected use DiffReport;
+  protected use crate_diff;
+}
\ No newline at end of file
diff --git a/module/move/willbe/src/entity/mod.rs b/module/move/willbe/src/entity/mod.rs
index 6073c0fa94..5a0be78e1f 100644
--- a/module/move/willbe/src/entity/mod.rs
+++ b/module/move/willbe/src/entity/mod.rs
@@ -1,6 +1,10 @@
 crate::mod_interface!
 {
 
+  /// Compare two crate archives and create a difference report.
+  layer diff;
+  orphan use super::diff;
+
   /// Operation with features
   layer features;
   orphan use super::features;
diff --git a/module/move/willbe/src/entity/package.rs b/module/move/willbe/src/entity/package.rs
index f5d904fab4..b9794b4d82 100644
--- a/module/move/willbe/src/entity/package.rs
+++ b/module/move/willbe/src/entity/package.rs
@@ -88,6 +88,22 @@ mod private
     }
   }
 
+  impl TryFrom< CrateDir > for Package
+  {
+    type Error = PackageError;
+
+    fn try_from( value : CrateDir ) -> Result< Self, Self::Error >
+    {
+      let manifest =  manifest::open( value.absolute_path().join( "Cargo.toml" ) )?;
+      if !manifest.package_is()?
+      {
+        return Err( PackageError::NotAPackage );
+      }
+
+      Ok( Self::Manifest( manifest ) )
+    }
+  }
+
   impl TryFrom< Manifest > for Package
   {
     // qqq : make better errors
@@ -744,7 +760,6 @@ mod private
 
     Ok( !is_same )
   }
-
 }
 
 //