A.C.
In babywearing, a mei tai is a type of carrier, and the Babyhawke is a brand of mei tai (think, facial tissue, brand name Kleenex). Mei tai's all have 4 cloth straps and a squarish or rectangular piece that holds the baby to you. You can tie it different ways to your body (front carry, baby facing you or outward; back carry; side carry).
A sling is a different type of carrier that goes over the shoulder and has a sort of pouch that the baby sits in. A sling is worn across the baby and the baby sits in the pouch, balanced against your opposite hip.
Check out http://www.thebabywearer.com/ for tons of good, helpful information. They also have volunteers who can help you figure out what sort of carrier might work best for you.