Difference between velocity and force in Character movement

I’m trying to add velocity do a character by accessing the character movement component and setting its velocity. However it is not working, so i used Force and it worked for my scenario.

I’m trying to make a character in paper 2d climb up a stairs. When he overlaps the stairs i zero the gravity and then i wanted to add velocity scaled with a movement input. However that didn’t work so i used a one force node to create impulse to get off the ground.

Can someone explain to me the difference and how can i use velocity for this scenario?

I have seen in other questions that people have suggested setting the movement mode to flying so that you can move in the Z plane

Such as:

I tried using movement mode to flying but i my flipbooks stop working when i do that.

After a lot of fiddling i’m using flying mode to solve the problem thanks dude.