Hello,
Basically, the difference between air and liquid cooling will be the substance used to dissipate the heat from your CPU to the ambient air. Liquid cooling will use a closed loop of coolant (water with chemical additive). Air cooling will use the air flowing through your case.
In most of cases, liquid cooling will be more efficient than air cooling, but will cost more.
I would suggest these two :
Air :
http://www.amazon.com/Cooler-Master-Hyper-212-RR-212E-20PK-R2/dp/B005O65JXI/ref=sr_1_1?ie=UTF8&qid=1412604293&sr=8-1&keywords=cooler+master+hyper+212+evo
Liquid : http://www.amazon.com/Corsair-Series-Extreme-Performance-Liquid/dp/B009ZN03AA/ref=sr_1_1?ie=UTF8&qid=1412604324&sr=8-1&keywords=corsair+h80i