x264 vs h264 & x265 vs h265

[tucows]

I don't understand why there can be 2 pre's of the same film with different codecs

eg.

(4F) (21176.32 MB) Poor.Things.2023.1080p.BluRay.x264-ROEN
(4F) (36065.28 MB) Poor.Things.2023.1080p.BluRay.H264-RiSEHD

and

(91F) (37171.20 MB) Watchmen.2009.The.Ultimate.Cut.2160p.UHD.BluRay.x265-TERMiNAL
(88F) (83170.00 MB) Watchmen.2009.ULTIMATE.CUT.2160p.UHD.BluRay.H265-GAZPROM

Usually the h265 is larger filesize. Comparing Watchmen (2009) using the nfo as a metric:

TERMiNAL: lower video bitrate, additional audio streams (+ DD5.1)
GAZPROM: higher video bitrate (48.9mbs vs 18.1mbs), no mention of bitrate for audio

Reading through "high.definition.x264.and.ultra.high.definition.x265.standards.revision.5.0.addendum.1-hdx" there's no mention of h265.

Am I missing something? Should h265 pre be labeled internal?

 

[9s6YGGKbfVTZ]

x264 is H264 and x265 is H265.

 

[Llama]

In this case H264/H265 - untouched, x264/x265 - transcoded. However, while codec is the same, the encoder is different - unknown vs x264/x265.

edit: just to add (from High.Definition.x264.and.Ultra.High.Definition.x265.Standards.Revision.5.0-HDX)

24.3.4) When tagging remuxed releases, the following applies to section 18.
24.3.4.1) H265 must be used in place of X265.
24.3.4.2) H264 must be used in place of X264.

 

[tucows]

Thanks for that @Llama

Easier tags for search now its all cleared up.