My dad had been sober for 39 years without a relapse.
Personally, I don't see a huge difference between a slip and a relapse. It is what it is. If a return to drinking for an alcoholic doesn't turn out horrible they were only lucky.
I had a sponsee who liked to play that word game with me. She's drink and say it's wasn't a relapse, it was just a slip. That's called denial where I come from.
Is one really better than the other?
I don't think so.