Not the same, both different. But POHD and other Realtek players can play both.

MKV commonly contain movies ripped from Blu-ray (I said 'commonly' not 'must be') and resolution is up to 1080P.

RMVB can have decent resolution too, but however, for TVB series they are commonly compressed to lower resolution and low quality because a whole series will take up too much space.

Hi, i just bought a playon HD last week and with a Lite-on blu-ray ROM, I have borrow a few Blu-ray disc from my friend and I copy whole BD files to my Play-on HD hard disk and when playing the files, the player come out error message "Bitstream Error" and stop there, what is the problem with "Bitstream Error"?