When you really like a person you get that feeling...it's a similar feeling to ordering a 6 piece mc nugget meal and when you open it up there is 7 and a switchblade.
I think they are two stages to the same thing. A crush is how you start liking someone but typically keep it to yourself. And when you start liking someone you are more prepared to be open with your feelings of attraction. To yourself or others.
Can we just say, "My heart goes doki-doki, nano!"
Ooh, so savage.