Metamathematics, by Kleene, is programming in maths. Theoretical computer science is maths. A lot of foundations work is programming. Coding itself is like an extended problem set from a maths class. LaTeX itself is programming.

The difference to me is one of directionality - maths research is seeing a far off island and getting there by hook or by crook; bridge, draining the swamp, inventing an airplane or boat, whatever it takes. Software engineering is like covering a plain with tiles - every feature is ultimately filled in and the underlying beauty is obscured by a fractal of complexity required by the ever growing requirements.