BobbyBadass It's actually more than just a bit more bitrate.
Depending on the colors, scene complexity and some other stuff, 10Mbps in h265 pack the same as 20Mbps to 40Mbps in h264
h264 @1Mbps - h265 @Mbps side-by-side.
When you pause the video you'll see the differences much clearer.
Mind it's only 1Mbps so they'll both look terrible nonetheless.
https://www.youtube.com/watch?v=AekAujM6ZcQ

a h264 VR scene at 30Mbps
and a h265 scene at 30Mbps
Will have roughly the same filesize
But one will be much higher quality.
Or
a h264 at 30Mbps
and a h265 at 10Mbps
Will be about the same quality,
but one will be much smaller.