Here are some real-world benchmarks from Geekbench for you.
the 2012 i7 15" (2.3ghz) is around 3334 for single core and 10680 in multi-core
the 2014 13" (2.6ghz) is around 3608 for single core and 7023 for multi-core.
So again, it depends on your usage. If you're "need[ing] it for [your] studies, listening to music, maybe editing a little bit and generally surfing the web." then the i5 will be faster. Pages, Safari, Chrome, etc aren't going to be taxing your CPU enough to warrant a quad core i7. IF you plan on exporting a lot video then by all means go with the i7.
Don't pay attention to one line answers with nothing to add "15" hands down", "13" all the way.", look at the research that I and others have provided you. I'm fairly certain that someone else pointed out that Apple will soon be deprecating that 2012 MacBook Pro, as this year the 2011's were added to the list...
I have a 2016 15" MacBook Pro 2.6/16/256/i7, and I'll be the first one to tell you that it's overkill for what I use it for, and I'm a web/graphic designer. And, as a student carrying books, don't forget about the added weight and bulk of that 15". It's 5.6 pounds versus 3.4 pounds for the 13". That's a huge difference in your bag with all of the texts and whatever else you're already carrying.