|I am assuming you are referring to movie files in both cases (you did not mention).|
Your DVD device only serves out data.
An Application (a Program) "reads" the data, "recognizes" it, and "translates" it to a watchable movie on-screen.
Which Program is associated with each?
(MPEGAV\*.dat for VCD)
(VIDEO_TS\*.vob for DVD movie)
Correct me if I am assuming all wrong.