Tricky CNC/Plotter question.

So i was thinking of making a 2d plotter and possibly writing the code by my self. while brain storming i got a bit confused as to how exactly steppers/cnc work.

Imagine there are 2 Steppers, A for x axis B for y axis.

for example if i give the command to my pen to move to point X, imagine this move takes 500 steps from Stepper A and 500 steps from stepper B , should the steppers move one step at a time, as in stepper A moves one step followed by stepper B?

What if the steps needed to reach a point are not the same, i.e. Stepper A has to move 300 steps and Stepper B 400 steps. Should controllers move the steppers in such a way that they both complete their steps at the same time? (Slows one down)

Forgive me if this is a stupid new to all this. :)

Check out Bresenham's line algorithm: