Python - Stay in loop Until condition is met

I am wanting to write a loop that stays in the loop until a condition is met.

Here's the code so far, and I'm not sure if all is correct, I have little experience in while loops:

x = 2885
y = 1440
difference = 0
while True:
     if x > y:
          difference = x - y
          break

So what I want is to keep subtracting my constant y from x until

y > x

and to have the final

difference = 5

Any help is much appreciated, thanks in advance!