Frame not exactly the same but don't think it would have made much difference for this test. I love Youtube but Vimeo clearly looks like the winner in terms of clarity IMO. Links of original videos below.
The original file is from a Runcam 3 with default settings. Uploaded the same file to Youtube and Vimeo.
The Youtube frame was taken after Youtube had a chance to prepare the 1080P 60FPS version and taken from that.
The Vimeo frame was taken from HD playback.
The bitrate looks higher to me on the Vimeo video.
Youtube: • Runcam 3 first test
Vimeo: https://vimeo.com/214123624