Different bitrate between m2ts and mkv ?

[Marcus Phoenix]

Hi everyone, first of all sorry for my english...

So, I just noticed that when i do "mediainfo" on my .m2ts file directly from the blu ray disc, the video bitrate is higher than the .mkv file is this normal ?

Another question : do the fact of using other applications during the "ripping" process can affect the final file in terms of quality ?

Thank you in advance