At Microsoft, I'd say roughly senior is able to lead a project end to end. Principal is being able to represent a department and take responsibility for making sure multiple projects are run smoothly, developers are growing, outages are prevented. There's some overlap, and it's really just a matter of scale and trust. As you produce results, you get more trust and more responsibility for larger things. Progressing through principal is much more about paying attention to the bottom line. It's your responsibility to make sure the things you're doing are things that either customers are willing to pay for, or things that greatly reduce COGS. These are all achievable by mortals so long as you're hard working, determined, and focused on the right things.
Beyond that, Distinguished Engineer I'd say is reserved for someone who works at a level beyond the most of us, whose work has produced multiple patents or been widely influential across the company or the industry at large. Fellow is someone who has done this continually throughout their career.