Well there is a difference, but yes they’re often used interchangeably now. That was my point, the poster was saying he wasn’t fit, I was saying he was, although he may not be sharp.
Saying someone isn’t match fit has always applied to someone coming back from injury. The idea is that they’ve recovered from the injury but they aren’t in a position to play a full game because they’ve not been training long enough etc. Match sharpness is really a totally different thing, and can apply to anyone who hasn’t played much. Match fitness is reached when the player is physically able to get through the entire game at a decent level, it can take weeks to gradually build up to that. Match sharpness is more a mental thing, there’s no physical issue, you’re just a bit out of practice and so not playing very well.