Love isn't a degree on a scale that when reached you can say, "Oh, I'm in love now." It comes in varying forms, amounts, and types.
If it were so simple that you could boil it down to one thing or the other, bookstores wouldn't have a "self-help" section.
Love is an emotion, but the decision to act upon it, to work with it, to strengthen it, or to end it lies with you.
You can love a friend, even love someone long enough that you might see yourself happy with them. That's where love becomes a decision. Or you can meet someone, and suddenly, at the most obscure moment, you realize without them you feel empty and alone.
You can also have "puppy-love", where you seem to fall in love at first sight, but really it's just a strong attraction that will most likely crash and burn at the end of two weeks. Sometimes you might at first despise each other, and then after a civil conversation, realize you like them- maybe even love them. (Hand to God I've seen it happen...)
Unfortunately, there's no accurate description of love. I generally expirience a sensation in my chest similar to if someone were blowing up a balloon inside me, I lose all ability to focus, and suddenly what I say to this person becomes the most important thing in my life, because if I say something stupid it's the end of the world...
I hope that helps!