I use Java where we only have packages. I know there are other programming languages that also include modules.
What's the difference?
It's hard to compare semantics in the void. (What other languages do you mean?) A "module" might be analogous to a Java class, or a Java package, or something else entirely, depending on that other language. Typically since "modules" tend to be from procedural languages, I'd lean toward saying Java class, but I think the line is very fuzzy at that point and you could argue package quite convincingly.