The primary difference between the AVCHD format and the MP4 format is the file structure (aka container format) used to save the video codec and audio codec. Although both formats record the video codec as MPEG-4 AVC/H.264, the AVCHD-formatted video is saved using a .M2TS file extension and the MP4-formatted video uses a .MP4 file extension. In addition, the audio codec for AVCHD is Dolby® Digital AC-3, while the audio codec for MP4 is MPEG-4 AAC LC.
IMPORTANT: AVCHD is suitable for creating AVCHD or Blu-ray Disc® (BD) recordings and watching on an HDTV. Whereas, MP4 can be saved as a single movie file and is much easier to move, copy, and upload to websites.
Specifications for both formats are provided in the tables below.