Bongs are legal to buy online. And the difference between bongs, well your way over your head. You first must make a decision. DO you want an ice bong? or just a regular water bong. The ice helps cool the smoke further rather then just water. The ice sits in the tub and is suspended above the water on whats called the "ice catcher." Secondly you need to decide if you want a carb or not. A carb is a small hole on the side that lets the smoke flow through when the bong is full of smoke. I suggest going without a carb, as i find them annoying. Without a carb, you just pull the slide out and all the smoke rushes into you lungs fast. SO: You've decided whether you want an ice or normal bong, and one without a carb. Next you need to decide the size. All brands of bongs come in all different shapes and sizes. But the best brand of bongs has been known to be ROOR bongs. They are very pricey some can be like 2000 dollars. Yeah.. i know! I would just suggest going to the local headshop and buying a bong around 40-200 dollars. I spent 175 and have a very nice bong. Anyways, name to me doesn't matter, to some they have to have ROOR and some others have to have custom. Its all personal preference, but make sure that its relatively thick glass (sometimes people drop it, or bang it) and make sure it comes with a decent slide(the little bowl that comes with it. Some bongs come with diffusers that help filter the smoke, but for a first time bong you dont need one, nor an ash catcher. Anyways have fun and buy from grasscity they have good cheap bongs. Its online, and yes its 100% legal as it is said to be used for tobacco. You must be 18 or 19 though. I forget.. and it likely depends on your area. OH fyi, bongs give more thc from the weed then any other method of smoking besides a vaporizer. Vaporizer is the best way, but bong is second best. And healthier then pipes and joints.