Rewrap clip, different bitrate and size?

Hi, I was thinking rewrapping just put the media in other wrap, but since info in Quicktime shows different size and bit rate I'm confusing about this procedure.

I'm looking for a way to import Sony MP4 timecode in Final Cut, when I import it from the SD camera, FCPX "rewrap" it to .MOV so it includes the timecode (from the XML, I suppose) , but then, both original media in the SD and the new rewrapped clip are different in sizes and bit rate, I can't tell the difference visually, but I can't tell it either if I export the media again to a good quality H264, so I assume some data loss is happening in the process.

One though is the video track goes straight as it is but the audio tack change format?

I'm I wrong?