What is difference between iterative model and waterfall

WaterFall Model: This is a flow based model, in which u
pass every phase once, and can not go back to that phase
again. That is why, it is used rarely now a days.

Drawback: If there is nay change in requirements, then u
can not make any changes in requirements.

Iterative Model: In this u can come back to previous
phases, and make the changes accordingly. In this we
revieved a final output product at the end of the SDLC.