Youtube video quality differs depending on browser?

Akatsuki1423

Estimable
Jun 8, 2015
2
0
4,510
When browsing a video on Chrome, there are only 2 quality options:
360p and 720p (the 720p seems like it's the same as 360p though...)

When browsing a video on Opera, there are more quality options, it even includes:
480p, 720p60fps and 1080p60fps

When browsing a video on Firefox, it has the same quality options as Opera.
480p, 720p60fps and 1080p60fps, etc...

This only happens for some videos, what's going on?