Difference in SumatraPDF-dll.exe and SumatraPDF.exe ??

[ISH2YU]

When I compile the GitHub code on my Visual Studio 2022, I get two exe files, which are SumatraPDF-dll.exe and SumatraPDF.exe. I wanted to know what the difference is between these two exe files.
Like why are two of them even being generated and what is the purpose of both of them ??

[GitHubRulesOK]

The dll is the self-installer component which would be unpacked during custom installation from the signed executable.

size varies depending on which compilation is run thus in theory more than a dozen variations but when signed only 3 variants are released. 32bit 64bit and arm.