This instructional video by Scuba.com differentiates the two types of spearguns. The first type is the pneumatic speargun which has no bands. It is powered by air and when you push the spear in it will give it pressure to shoot back out. A banded spear gun will have usually one to three bands you pull back and put into notches on the spear. Both are great spearguns it just depends on what you are looking for.
