How different does a beer have to be before it's a different beer?

I’m referring partly to fresh hop beers. I know if the ABV and IBUs are the same, then it’s the same beer. But what if it’s called the same, but the ABV or IBU is different, and it says that hop variety, fresh hop vs dried, or malt type is different?

Different hop and malt type with same base beer are definitely different beers.