When you are denoting size, there is little difference between "little" and "small". The most significant difference between the two comes into play when you're describing quantity. Another bit about "little" is that depending on whether you have the article "a" in front of it, the meaning flips: I have a little experience teaching English. I have little experience teaching English. The two sentences have opposite meanings. The former indicates your having some experience, whereas the latter indicates your having no experience. The word "small" has no such issues.