MTS vs M2TS
Blu-ray Disc Audio/Visual or BDAV is a container format for Blu-ray video files for the consumer market and is based on the MPEG-2 transport stream container. With BDAV, there are two file extensions in use; MTS and M2TS. It can be confusing to some, thinking that there are major differences, advantages, and disadvantages of using one over the other. But in truth, there is actually none as the two are basically identical to each other.
M2TS is the proper file extension for BDAV and is allowed in modern file systems that use long file names. A problem arises when you use a legacy file system that uses the 8.3 naming convention. It basically means that you can only have 8 characters before the dot and 3 characters after that as its extension. As M2TS consists of 4 characters, it cannot be used as an extension in legacy file systems. This led to the creation of MTS as a substitute extension.
The need to make BDAV compatible with the 8.3 naming conventions stems from the use of AVCHD of this format. AVCHD camcorders use memory cards or other forms of digital storage instead of the typical tapes for recording videos; directly encoding the file into the BDAV format. Since memory cards use FAT32 for compatibility purposes, AVCHD is forced to use the 8.3 naming convention for saving the files. Blu-ray discs can use long filenames, thus they use the M2TS extension.
A difference worth noting between MTS and M2TS is a direct consequence of AVCHD and Blu-ray; because AVCHD uses a simplified version of Blu-ray encoding. AVCHD only has 1 video encoding algorithm and 2 audio encoding algorithms. So if you get an MTS file, you can reasonably hazard a guess that the files comes from an AVCHD camcorder and that it doesn’t use any of the more complex encoding algorithms that are used in Blu-ray discs.
To sum it all up, MTS and M2TS are just two extensions used for the same file container format. The differences between the actual contents are not caused directly by the extension but by the standard that encoded the file.
Summary:
1.The two are different extensions used for the same container format
2.MTS is the extension used in legacy file systems while M2TS is used in more modern ones
3.MTS usually means that the file comes from an AVCHD camcorder while M2TS is from proper Blu-ray