Ok. So at the time that Knight retired, his Texas tech team sat at 12-8, which is about a 67% W/L record. He had just recorded his 900th win. A huge milestone. So retiring after all those years and being one of a handful of coaches to win 900 games is pretty significant.
When Spurrier quit, his team was sitting at 2-4 and was likely staring at a losing season. He did not reach any kind of sports milestone. He was looking at a really tough year and seemingly didn't want to deal with it.
I really don't see how they are even remotely similar but you are entitled to your opinion as I am mine.