well, i think this is all attraction.  though we all say i love this girl/guy or that girl/guy and so on, there is something about him/her which  attracts us.  i was also in love. someone get attracted with look, some with personality, some with  intelligence, or something else.  there gotta be something which attracts us at first time and then it starts from there.  if some guy or girl  who is very good in sports, or in music..that could be attraction as well.  so, it starts with something. 

however, there is another way, people spend so much time together and they start liking each other's company and start thinking about each other more.  they like each other's behavior also.  they later fall in love.  so, this is different kind. 

OC, you are also mentioning about look here.  you did nt know much about her and you were in love?  or crush or attraction or infatuation?  i dont know what was that.