That's a good question with no good answer. It's estimated that there are about 1200 species of bamboo, and many of them either look very much alike, or are simply hard to identify. There are books and photo databases, but one typically finds that a lot of bamboo look a lot alike. Many other types of plants are identified by their flowers, but, since bamboo hardly ever flower (think once every 20-150 years), that's not a very useful method either. Some bamboo have unique characteristics and can be identified on sight, but for many it's a process of looking at a variety of characteristics (culm color, sulcus color, node appearance, leaf size, branching pattern, presence or absence of hairs, shoot color and appearance, etc.) and narrowing it down or coming to some conclusion by a process of elimination. Also, some bamboo look different as young plants compared to older plants, or change color over time, so it's best if you've observed them for a while. Having said all that, you could try posting pictures of them (full shots and closeups of culms, nodes, and leaves) and we'll see if we can help at all.

See how kind Kudzu is? I was afraid I would be rude if I tried to respond to your post, Rudy. I was kind of scared by your handle. Lately here, I saw someone mention that culm sheaths are sometimes an excellent way to identify bamboo. That kind of woke me up. If I wanted to write a book on bamboo identification (supposing I had enough knowledge to do that), the chapter headings would include (identification by) culm sheaths. Probably, someone is working on that book right now, down at the American Bamboo Society. But to regress: I often think it's pretty lazy to post really broad questions like yours, then some kind soul will materialize out of the internet ether and show me that I am growing impatient and gnarly, maybe even rude ...