A major difference is that a senior developer does not limit themselves to just software development. They learn something about ops, they learn about tuning a

A major difference is that a senior developer does not limit themselves to just software development. They learn something about ops, they learn about tuning a database (whether SQL or noSQL), they learn about business problems and so on. The most important difference is that a senior software developer is evolving into being an engineer who understands the total solution space, not just the software. By choice, some people stick with software development rather than moving into software engineering or devops, but a senior person makes that as a choice, not because they are ignorant of engineering and devops. What is the difference between a software developer and many other professions? A software developer is constantly learning new techniques, new languages, new technologies. Therefore a senior software developer knows a lot more than a junior one and has more hands on experience with more aspects of the trade.