I think their command line syntaxes differ. I'm not 100% sure though... I'm porting Descent 1 to my OS and I just want to get it to build under Windows first (otherwise it's a hopeless goal).
I don't know for sure but MASM doesn't change much in minor revisions. I have ML 6.14.8444 and LINK 5.12.8078 and never have had problems assembling and/or linking MASM sources.
On the field with sword and shield amidst the din of dying of men's wails. War is waged and the battle will rage until only the righteous prevails.