NTSC vs PAL

A clip that originated from PAL footage will probably have a frame rate of 25 fps, one that originated from NTSC will probably have a frame rate of 29.97 or 30 fps.

You can find out what the clip's framerate is in the "Window > Show Movie Info" window.

As for which one is better, PAL is a newer format (if you can call 38 years old "new") & has a larger frame size & better chroma, but a lower frame rate than NTSC. Which is "best" really depends on the format of your original footage, and your intended delivery audience.

If your footage was shot in NTSC and you're playing on regular TV's (e.g. on Video CD- MPEG-1 or DVD- MPEG-1 or MPEG-2) to an audience in an NTSC country (e.g. USA), there's little reason to do a standards conversion. If your audience is using computers for replay, ditto. Computers don't care about PAL/NTSC differences no matter which country they're in or the video standard used there.

If all that is Greek and you were actually meaning MPEG-4 format, well that's a whole different kettle of ballparks.

PAL = 25 fps. Usually 720x576 but also 704x576, 352x576 and 352x288 might be used.

NTSC = 29,97 fps. Usually 720x480 but also 704x480, 352x480 and 352x240 might be used.

Notice that QT Player doesn't report the correct resolutions for MPEG files (it reports them scaled to 4:3) so use apps like MPEG Streamclip or mpgtx to see the resolution.

Usually you want to compress to the same standard as the input is.