Your question is not sensible, as if the cassette is different one way it will not be offer lower gears, another way it will. Even if you ask which cassette(s) would be more suited to climbing than 12-25, it's not the question but the answer that is complicated. I directed you to a search because all we would do here is repeat what is in those references.

Although larger rear cogs (or smaller front chainwheels) give you lower gears you have to understand gearing and how the gears relate to each other in respect to gearing range, overlap, and shifting patterns in order to make decisions about what combo will work for you in particular. You can choose how much you want to learn - we can only guess what you need to know and how you need to learn it. If someone here wants to tutor you or act as a consultant on gearing that's fine, but you still need to learn how low a gear you need, how wide a range you want to tolerate, and then look at the compatibility between the derailleurs, cassette, and chainwheels.