In my experience the distinction between Senior Engineer and Staff Engineer is meaningful, because they do very different jobs.

A Senior's work is scoped to one team, reporting to an EM, and they do the usual stuff - work on tickets, run stand-ups, deliver features. The Staff engineers have no home team (they are expected to work across multiple teams), they report to the CTO, and they have a lot more freedom in what they spend time on. In fact the dynamic is reversed; rather than being given work, they're accountable for identifying the most important work and doing it. It also comes with a whole lot of new meetings.

I'd argue that Senior Engineer is more of a bullshit title, if titles are supposed to be an indicator of what your job involves. At Senior my job didn't change at all. It's just a title to recognise people who have been around for a while.