There's not much difference since generating the abstract syntax tree is usually the hardest part. Once you've done that, it's just a matter of generating a string representation for each node in the tree for the given target language.
Did you ever try to translate one language into another? Usually it's just generating the AST that is the hard part, then you can just spit out code and let the compiler for the target language do the hard stuff.
I'm not clear where people get this idea from. In the case of Wasabi specifically, it uses Code DOM, which can generate IL, C#, and VB.NET out-of-the-box, and can be extended fairly easily to target other platforms as well.