Format overview
What are H.264 and H.265?
H.264, also called AVC, is a video compression standard used by cameras, streaming services, Blu-ray video, mobile devices, and web platforms. H.265, also called HEVC, is its newer successor and was designed to compress high-resolution video more efficiently.
Neither standard defines the file extension. An MP4, MOV, MKV, or transport-stream file can carry H.264 or H.265 video, so the container and codec should be checked separately.
Compatibility
Compression and quality differences
HEVC uses larger coding structures and more prediction options than H.264. At a comparable visual quality it can often use less bitrate, which is valuable for 4K, 8K, HDR, and storage-limited delivery. The tradeoff is higher encoding complexity and more demanding decoding.
Actual results depend on the encoder, preset, source material, resolution, and bitrate. A poorly configured HEVC encode is not automatically better than a well-configured H.264 encode.
Practical use
Which codec should you choose?
Choose H.264 when compatibility, fast editing, or older-device playback matters most. Choose H.265 when smaller high-resolution files are worth the additional processing and every destination supports HEVC.
For editing, proxy or intermediate formats may respond more smoothly than either delivery codec. For web delivery, verify the platform requirements before choosing the container and codec combination.