this is the difference between the 2 consoles and games   pal - australian     ntsc - american

The Americans, Canadan & Japan use "NTSC" (National Television System Committee).  Western Europe, Australia, UK & New Zealand use "PAL" (Phase Alternating Line).  Plus there are 3 types of PAL systems.

The main difference is lines per inch (LPI) on the screen and the signal frequency (Mhz).  (I have no idea why different country have different TV Signal.)

Technical Stats are as follows.

NTSC

Lines/Field 525/60
Horizontal Frequency 15.734 kHz
Vertical Frequency 60 Hz
Color Subcarrier Frequency 3.579545 MHz
Video Bandwidth 4.2 MHz
Sound Carrier 4.5 MHz

PAL

Line/Field 625/50
Horizontal Freq. 15.625 kHz
Vertical Freq. 50 Hz
Color Sub Carrier 4.433618  
Video Bandwidth 5.0 MHz
Sound Carrier 5.5 MHz

Most Australian TV/VCR & DVD are fairly much universal.  They will accept both a Pal or NTSC signal.  (Or at least switch between the 2.)  Where as Most USA equipment will only accept NTSC.

At the moment I know of know hardware mods / adaptors which you can purchase for the pal super nintendo system to allow you to play 90% of american - ntsc games on a pal console

The cartridges are of differnet size, so you can't make the mistake of trying to insert it into the wrong console