It's certainly not a precise comparison, you're right. Nevertheless, compare for instance x264 and x265. Exactly how large the difference between the two is de

It's certainly not a precise comparison, you're right. Nevertheless, compare for instance x264 and x265. Exactly how large the difference between the two is depends on the type of content, bitrate, resolution and other factors, but it's hard to find any case (encoding speeds aside) where x265 wouldn't be substantially better, to the point where we generally call H.265 a better codec. I was expecting a similar kind of leap with AV1. This comparison may not be conclusive, but it looks like that's probably not going to happen.