When considering VHS tapes, there are 5 video standards in use in the world. These 5 fall into 2 groups.
Group Standard Example Countries 1 NTSC USA, Japan PAL-M Brazil 2 PAL UK, Most of Europe SECAM France MESECAM Former Eastern Block There are many variations on these standards when it comes to broadcasting (eg: NTSC, NTSC 3.58, NTSC 4.43, PAL, PAL-M, PAL D/K, PAL I, PAL B/G, PAL-N & SECAM) but these variations are not relevant to what goes on a VHS tape.
Group Tape Speed Frame Rate 1 33.35 mm/sec 30 Frames/sec 2 23.39 mm/sec 25 Frames/sec Group 1 and Group 2 tapes (and tape machines) are incompatible because of the differences in the Frame Rate and Tape Speed.
Play a VHS tape on a different standard machine within the same group and you will probably get a Black and White picture. Play it on a machine from the other group and you will get no picture at all.
From a VHS tape perspective PAL-N is the same as PAL.
Click here for a table of the standard used by each country.