There is not a clear boundary here.
I talk to people who have "quantitative analyst" on their business card whose work is essentially looking after a few buggy spreadsheets.
Nor is it constant over from one month to the next where "theoretical" quants can be debugging C++ or sigting through data, or puzzling out some hard maths.
Some quants aren't called that, instead labelled as "strategist", but of course many strats aren't quants. Senior quants often don't have this in the job title.
You need to look not only at the work they describe, but at your future bosses and peers to get a better feel for what work you are signing up for.