[karmakaze]

I think of 'engineer'/'engineering' vs 'developer' in the software world as in the non-software world. There are inventors, hobbyists, researchers etc. But when it comes to coordinated projects with sizable team(s) or over a longer span of time, that's an engineering project.

So the best way to become a better software engineer (by this definition) is to work on projects with others (possibly opensource though that has additional aspects) or projects over longer periods of time. You find that your former self could well have been another developer, whose legacy you have to deal with. You learn to make things that age better, or designs that are easy to communicate and build upon.

I wouldn't preclude a front-end dev from being called a software engineer, but at the same time one that has experience in full-stack is much more aware of the tradeoffs that choices imply, to be a better one.