After having created the insufficient-memory including tag excerpt and wiki, now used by 10 questions, during re-tagging I discovered the storage-full on the last question, which is used by 9 questions currently.
Both tags are not really equivalent (insufficient-memory directly refers to the "insufficient memory..." error, thus dealing exclusively with the devices' internal storage -- while storage-full is much broader (at least from its name, though ~80% of the questions tagged such seem to explicitly refer to "insufficient memory", and the remaining 20% at least implicitly).
My idea was to merge the two, and convert storage-full into a synonym for now. So if we really feel we need a separate tag by that name at a later point, it would be easy to retain. At the moment I do not see much sense in a separate broad "storage-full" tag (my, if the card is full one needs to delete something, right? Or buy a larger card).
Please keep insufficient-memory as the main tag / merge target, as it already includes a tag wiki with "first aid" as well as a wiki excerpt :)
Internal memory space is loworinsufficient memory available(app-install via playstore). I fully agree the term "memory" does not apply in this context (as really, internal storage is meant). But if the error message speaks of "insufficient memory", what do you think a user will look for in tags?