[MichaelGG]

Rosyln's a compiler/framework for certain language tools or something like that. Msbuild is like a Make type tool that actually calls the compiler, passes in flags and input files, determines what else needs to get done, etc.

[julbaxter]

Does it mean msbuilb uses roslyn somehow?

[MichaelGG]

I understand that Roslyn powers or is the C#/VB compiler. Yes, the build system will often call the compiler as part of the build.