A discussion last year decided that jsom and csom are not equivalent, and that they are both subsets of the broader client-object-model.
(Whether the distinction is clear to questioners is debatable given that plenty of questions are tagged as both JavaScript and CSOM, but that's outside the scope of this discussion.)
However, there's also a client-side-object-model tag floating around. For the sake of consistency, I propose that this tag be made synonymous with [csom].
