does the increase in fees vary for different degrees?

It'll differ between universities I'd assume.

no no, I think you misinterpreted my post.

I meant by degree and not uni, for example a maths degree might cost less than a chemical engineering degree because engineering uses a lot more resources than a maths degree

is this how it works?

That's what I meant. I'd assume it'd differ between universities - some may charge the same for most if not all degree courses, whereas others would vary the prices based upon whatever factor they choose.