I see that inscriptio does exist in classical Latin in the sense of "inscription", but titulus was actually more common for that. I think inscriptio refers more to anything that is inscribed, rather than the inscription/titulus/epigramma that has particular characteristics of its own. I don't know, maybe something to consider.
Everything that is written (in general). Title of a book. Inscription. Stigmata (?). Accusation (probably inscription in a trial register?)
Title. Inscription. Dedication (inscription).
So, both seems to mean "inscription", and could be synonyms, but "inscriptio", as a word formed from the verb, like "writing" is formed in the English language, seems to have the broader meaning of "everything that is written", you are right. ("Inscriptio" means = something that is written on.)
But can be used as "inscription" also.
I believe that's the literal translation. On some other exercises, that type of literal translation is allowed, but I haven't tried it here.
It does help to think of it that way when figuring out how to conjugate these, when that's part of the exercise.
Spanish has a lot of these kind of verbs.