The way I can tell if it's classical or not is, if I'm in the mood to listen to classical music, whatever I'm listening to (if I was the one who selected it), it's probably classical.

One of the things I find with a lot of classical music (or the kinds I like, anyway), is that it makes me feel expansive in one or all of a few ways. Spiritually expansive, mentally expansive, and emotionally expansive. Works for me. (Most really weird modern classical music has the exact opposite effect on me though.)