How do I factorize (further) this? I do not understand the steps, I know the answer although.

The question goes:

1)

(x-b)^2-x+b

=(x-b)^2-(x-b)

=(x-b)(x-b-1)

I do not understand the steps from 2nd to 3rd.

2)

x^2-y^2-(x-y)^2

=(x-y)(x+y)-(x-y)^2

=(x-y)[x+y-(x-y)]

=(x-y)(x+y-x+y)

=(x-y)(2y)

=2y(x-y)

I do not get the step from 1 to 2.

Explanation would be appreciated.