some will, some wont.
you just have to call the manufature and get the real word.
for example...
The BLACKHAWK SERPA CQC level2 fits both my M&P 9MM FS, and my M&P 45 Compact.
But I also have a SAFARILAND 6377 for my M&P 9MM FS and it will not work with my M&P 45 C.
And fianlly, The CROSSBREED Supertuck is my IWB holster and with a little adjustment it fits them both great!
Good luck on your search... its worth the effort..
take your time and get what you REALLY want... a holster is like shoes.
If you are uncomfortable in them. you wont wear em.