This question is a paradox. You ask the most newbie question ever whilst stating that newbs get confused about this newb question.
Sports betting is gambling. The only possible way in which it could not be considered as such is if you are 100% certain that you are betting with an edge on the market, at which point you can call it simply business.
I concur, I mean I do not know how someone could be confused about something like this, sport bets are offered by casinos, and casinos only offer gambling games so by logic alone we can deduct that sport bets are a form of gambling.
Now I will admit that sport bets look different than other casino games in the sense that we are openly given the odds that our bet has, something which does not happen in blackjack for example and that you would need to deduce on your own, but except for that little detail sports bets are nothing else but yet another gambling game offered by the casinos.