Phelps and Bolts are apples and oranges. That's like comparing Michael Jordan with Jerry Rice.
The one thing no one said though is that Phelps competes in so many more events because he's a swimmer. 4 x 100 medly, 100 and 200 meter freestyle, backstroke, butterfly, etc. Of course he's gonna win more medals. He competes in more medal winning events. Plus, swimmers can last in 2 or 3 olympics and still be dominant. Most runners NEVER win back to back Olympics. The shelf life of a runner is way shorter than a swimmer. Either way, they're both GOAT - just in different categories.