[noctune]

Personally, I use "regex" for the informal string-matching/rewriting engines found in most languages and "regular expression" for the formal definition.

[FeepingCreature]

By which, of course, this submission title is a lie.

[necovek]

I don't think the GP is the original poster, so them claiming how they "personally" differentiate between the two does not make the submission title a lie.

We don't know how original poster differentiates.