MP4 and MOV look like two different video formats, but they are closer than most people think. Both are containers — boxes that hold a video stream, an audio stream and some metadata. MP4 (ISO/IEC 14496-14) was actually based on Apple's QuickTime MOV format.
The short answer
- Use MP4 for sharing, uploading and playing on non-Apple devices.
- Use MOV if you edit in Final Cut Pro or need professional codecs such as ProRes.
What's really different
| MP4 | MOV | |
|---|---|---|
| Standard | Open ISO standard | Apple QuickTime format |
| Common codecs | H.264, HEVC, AV1 + AAC | H.264, HEVC, ProRes + AAC, PCM |
| Plays on | Practically everything | Apple devices; most others with the right codec |
| Typical source | Phones, YouTube, screen recorders | iPhone camera, Final Cut, pro cameras |
Why MOV files sometimes won't play
The container is rarely the problem — the codec inside is. iPhone MOVs usually contain HEVC (H.265). An older Windows PC without the HEVC extension, or a smart TV from a few years ago, simply can't decode it, whatever the file extension says.
Converting without losing quality
Because both containers can hold H.264, HEVC and AAC, converting MOV to MP4 is usually a remux: the streams are copied into the new container, not re-encoded. That's what Spool's MOV to MP4 converter does by default — it takes seconds and the picture is identical. If you need maximum compatibility (for example for an older TV), choose High quality to force an H.264 re-encode.
File size
For the same codec and bitrate, MP4 and MOV files are virtually the same size. A MOV that's much bigger is usually ProRes or a higher bitrate — that's when compression helps; try the video compressor.