I don't. One would have to ask the company in question for the job description because, like you said, the titles have been used interchangeably. So, while having a puritan description for "you have to be this tall to ride the SRE title", there are system engineers titled people that have done their job like SREs for years who will not understand the fuss. I agree that good common definitions are good for the work practices, but not people. Job roles are fluid and something new comes along all the time. Instead of defining what a DevOps Engineer does, we need to define what existing real people change in their knowledge and behavior.