advantages and disadvantages reference vs reflection c#

What are the advantages and disadvantages to use reference or reflection with c#?

I have c# project that i want to use on my project, it come like dll.

I ask to know how to load/use on this dll (add reference or reflection)?

If the dll that referenced from my project changed(update version but not broke the api, only change inside the functions or add some private functions) will I need to recompile my project?