Your MP4 video is more compressed than your AVC video. (AVCHD is designed to be edited while MP4s are less so.) But if you can't see a difference in the results, there's no harm in using the MP4 workflow.
Thanks Steve. You state AVC is better for editing than MP4 but in APE I see no editing differences whichever format I import. Please explain.
On another forum, Sean Nelson wrote a comment. Rather than write it myself, I'll quote him. "AVCHD and MP4 are really the same basic video file format. [Both are "containers" and use the H.264 codec.] The major difference between them is that AVCHD wraps the actual video files in a folder structure with metadata that can logically link separate video files - this eliminates the restriction of scene length that's caused by the 2GB file size limit on most SD cards."
AVCHD was developed jointly by Panasonic and Sony as the industry was transitioning to Blu-Ray and SD cards. As we are transitioning to 4K, Panasonic has shifted to MP4. My Panasonic 4K cameras don't use AVCHD for 4K, but still have it as an option for HD shooting.
More important than AVCHD vs MP4 are the choices your camera gives you for bitrate. The higher the better! However, you may not actually see a difference until the day in the future where your computer screen or TV is upgraded to a newer technology.
Thanks for that. Most interesting. Explains why I see no quality difference. I shall change permanently to MP4 and see how it goes. Thanks for your help.