What is it called when you play both offense and defense?

Answer 1

This is often called playing "both ways". It is also sometimes referred to as 'Iron Man Football". It is quite common at lower levels of the game, but as one moves up the game gets more complex, more demanding, and more specialized. Generalists have a harder time keeping up with specialists, and can usually only do so if they are uncommonly great athletes. At the NFL level there have been a few players who played full time on one side of the ball and were situational contributors on the other, but it is usually a gimmick.

Answer 2

in the NFL you dont play both sides of the ball