Welcome to the forum! To answer your question about how we distinguish notes; it varies per person. I myself smell a lot of similar things, then begin to question what those notes are. For example, you may have different top notes in two fragrances, but if the heart notes are the same, you might be able to detect it...
Also, I love Nightflight. It's one of my top scents; the bergamot adds a spicy tone, where most others fall flat (such as Onyx and Body Kouros), while the fruity top notes electrify the scent. Live Jazz, though, I can't speak for... I don't own a bottle; but I have tried it before... I'll leave the opinion to someone who actually owns a bottle.
Hope that helped!