The people who make up the modern president's cabinet are the heads of the major federal departments and

The people who make up the modern president's cabinet are the heads of the major federal departments and Secretaries, commonly this position can be equivalent to a minister, in some countries they are called Secretary for foreign affairs, secretartio of defense, and in others they are called Ministers, Minister of Defense, Minister of Energy, etc.

They made a checks and balance system to equal power within the branches. the "check" meant that one branch would watch one branch and "balance" them if they were too powerful. if you want more info on this, i would just google checks and balance system.