AACOMAS vs. AMCAS in one line
AACOMAS uses grade replacement for repeated courses. AMCAS counts every attempt. Otherwise the rules are similar: BCPM split, plus- minus 4.0 scale, P/W/AU excluded.
Grade replacement explained
If you retake a course, only the most recent grade counts in your AACOMAS GPA. The earlier attempt still appears on your transcript but does not enter the math. You must flag the repeat as such in the AACOMAS application, it does not auto-detect.
BCPM classification
AACOMAS uses the same BCPM grouping as AMCAS: Biology, Chemistry, Physics, and Math. See the AMCAS page for the full classification breakdown, the rules transfer directly.