Because length can be different. Let's compare the result of aa and c:

using a = 1, etc.
2 < 3
using a = 97, etc.
194 > 99

But how are 1-26 and 97-122 not simply relative?

Because:

Each letter of a word scores points according to its position in the alphabet: a = 1, b = 2, c = 3 etc.

I've written a lot of code to solve this task :(

You can spend less time than you think. For this, you should think again !!!

Very simple task !!!