From my limited experience with these tags, they mean different things.
"Confusables" is about words (or other things) that speakers or learners commonly confuse. For example, "what is the difference between 'deprecated' and 'depreciated'?" People asking these questions want to learn about some distinction so they can avoid making the mistake of confusing these terms.
"Ambiguity" is about ambiguous structures. Ambiguity is not necessarily, or even usually, a mistake. People asking about ambiguity may want to know how to interpret an ambiguous sentence, or they may want to know about alternative ways of phrasing that are less ambiguous.