A glass hand pipe can be a chillum pipe, or animal pipe, or bubbler pipe, or any other shape smoking pipe, if you can held it in your hand, its hand pipe,  the most popular glass hand pipes are Spoon pipe and chilum pipe or onehitters.

     Spoon pipe, the most classic hand held pipe, just like the name, the pipe it self like the spoon you use everyday . In other words, they have a neck with a round bowl, as well as a mouthpiece and a carburetor, or a carb hole on the side. A carb hole is a small hole found on the side of the bowl when you inhale you release it,  This is example of glass spoon pipe,

  Chillum pipe or one hitter,  although they may look the same, but they are different. A Chillum is a simple hand pipe with a front-loaded bowl and no carb holes, one hitter is about the same almost identical to the chillum pipe,  but you have to light it up after each use, the loads in the front chamber are lmited to one use only, and chillum you can use multiple times,

This is example of onehitter pipe, you have small front space for one loads,  onehitter just like the name one use each time,

this is perfect example of chillum pipe,  you have more room in the fronts, so when you light it up, it can inhale it avenge 5-8 times compare to one hitter,

those are most popular type of glass hand pipes.