I don't wanna add anything here. You are correct on the idea you already have. Keep going 👍

I typically tell people that engineering is applying physics. If you aren't directly interacting with the physical world, you are most likely a developer.

Working on an app, no matter how complex (or unessarily convoluted) generally makes you a developer. If you aren't thinking about impact of clock cycles, actuation/hardware interfaces or sensing, there is a high chance that the work you do has little to no risk or a chance of failure that is governed by the physical world. As said in other comments, engineers design and sign off on things. There is an implication that there is an unknown constraint, unlike a fully observable software environment.