Umm you are right. Huracan is cheaper and has less power, but there is not much of a performance difference. Huracan is lighter, it has a 7 speed, dual clutch and electorinically adjustable suspension.
Aventador on the other hand, is the flagship car, V12, doors and it is most Lamborghini lovers dream car:) But if you can get a huracan in 1/2 less price with a small performance diference, it is quite reasonable for me to go with Huracan.