H.264 same size as H.265

[PierreDaniel]

I've exported a clip of 15 minutes in 1920x1080, H.264, with the preset "Match Source, Adaptive High Bitrate" (which turned out to be about 16 MBit/s). It turned out about a size of 1,8 GB.

So I thought, let's try to make the file size smaller, and chose HEVC (H.265), also a bitrate of 16 MBit/s, with VBR. The clip turned out amost the same size, only a bit larger... 

With CBR with settings on "good", it's also the same size... 

So I'm not sure what to do – I thought that H.265 would render into smaller file sizes... What did I do wrong?

Any hints would be appreciated!
Thanks a lot.

[Sami Succar · Accepted solution]

It's the bitrate that determines the file size, if you're aiming for a lower file size, you need to lower the bitrate regardless of the codec.

Briefly, the difference between H.265 and H.264 is that H.265 can deliver a better quality in the same size (same bitrate).

[PierreDaniel]

Ah, thank you. Now I get it. 
So in other words, I can get the same quality, but smaller file size when I reduce the bitrate. Makes sense.