they are same things.

 imagine the velocity time graph is like a mountain. ( i mean linear increasing, then peak, then linear decreasing)

the 2 expressions will gave the same result.

note that the calculus operator as far as my knowledge expends is only an operator and does not have any algebraic meaning.

there is no maening to x + d/dt + d/dx + y = 0

so mod function will mean nothing.