Answer:
Differences:
The USA uses the Electoral College while Mexico uses the popular vote to elect the president
The Mexican president can directly appoint cabinet members while in the US, the senate needs to approve the president's choice
American president can run two terms, four years each, while the Mexican president has one term for six years.
Mexican politics are dominated by four major political parties that vary quite a bit in belief while American politics are run basically entirely by two parties that are more similar than different.
Similarities
Both are federal presidential republics
Both have a constitution
Both have different levels of governmental power (Federal, state, local)
Both countries, as they are today, were born out of revolution
Both countries are democracies