This used to be easy to answer. The first is a university and the second is a trade school or apprenticeship. However, the latter has fallen out of favor (for some reason?), and universities are having to pick up both roles. I don't think this is the right answer, but it's the only one that seems to have political / financial support. Interestingly, software rediscovered "trade school light" in the form of coding bootcamps.

> If lawmakers wanted to help the student debt crisis, a great start would be making student loan payments tax-deductible ... instead of just having student loan interest be tax-deductible.

Tuition is deductible. So you effectively deduct the principle payments the year you pay tuition. It makes perfect sense for only the interest to be deductible the second time around.