Both are temporary, but love lasts longer. Falling in love is accompanied by changes in human metabolism, similar to the effect of certain drugs. Those alterations in our biochemistry give us an illusion of being happy, and similarly to drugs, the impact cannot soothe us forever.
And similar to drugs, the feeling may be addictive, so this is why we encounter many people who are getting high in a neverending cycle of falling in love, getting disappointed, and making the same mistake again.
As for the attraction, there is nothing mysterious about it. Our brains are programmed on a very low level to appreciate certain features in the opposite sex that can be interpreted in the following manner: We perceive a person, evaluate the person according to hardwired criteria, and if the person is approved by the brain, the body starts the secretion of hormones that we interpret like an attraction.
And since we want to enjoy the pleasant feeling as often as possible, we start to seek the company of such a person.
If the relationship brings us more joy than sorrow, the brain enforces its stimulation to the state we call love. All of this helps us and makes us reproduce with the best possible partner available, no matter how irrational it may seem for an independent observer.
Unfortunately, our brains, on their basic level, do not calculate the attraction in the way we would want them to do, so their very primitive algorithm forces us to follow attributes we tend to dismiss on a higher level of our conscience, such as physical build or length of hair.
The problem, as you should understand by now, comes with our inability to reprogram our brains, so even if we scold ourselves for having the urge to watch an attractive specimen, the brain thinks otherwise (pun intended) and keep shooting the happy juice into our veins.
And conversely, if the brain doesn't like the object, it perceives even though our rationality vehemently disagrees, we simply cannot and will not feel anything. Translated to our speech, the brain says: "Yes, she or he may be nice, caring, and wonderful, but no - there will be no babies because his or her eyebrows are too thick."