Sorry - an ATPL is NOT even close to a degree in terms of content or time to qualification.
Not entirely sure why you would even want to compare the qualifications - I guess a potential employer could see an ATPL as demonstration of one's ability to learn - assuming a particular degree was not a prerequisite for the position.
I am surprised that an ATPL could even be equated to 25% of an undergraduate course load, let alone a Masters (comparisons to a PhD are just plain ludicrous).
Having said that though, it doesn't really matter as my airline job is so much more satisfying and lucrative than my degree based vocation. It also gives far more quality leisure time.