In my early years my title was computer programmer. Then for a long time my title was developer because I did more than program. Eventually I used computer scientist. There's so much here's that I really can't lay out in a tweet.

It's the cocktail party fallacy. "What do you do?" Rely on context, define domain, role, and be specific. It ain't easy and I am very bad at it myself. I process language as literal, concrete. But write and speak in a bizarre combination of abstraction, education, and street.

A developer 'develops' frameworks, not use them.

I have often used ‘software developer’ to focus on systems with off the shelf hardware & ‘developer’ for novel hardware and associated software. I think this will become more common with RISK-V. Are there common ways of distinguishing library developer v library consumers?

Yes. You just did it yourself. Define the domain and the role. The domain anchors the term in far clearer ways. Library dev, library consumer. Alone, there is no defined domain. "Developer" is an abstraction as a result. Gold star for answering your own question!

MS DOS developer

Someone who buys big blocks of land and subdivides them hoping to make a profit.