different between al products?

Swish Pix is an electronit photo album creator.
Ergo it's functionality is rather limited.

Swish Lite was the predecessor to swish 2.0
When swish 2.0 came out swishzone had the option
to discontinue it however they realized that many
people enjoyed it's ease of use and were not interested
in the level of complexity or offerings that swish 2.0
has to offer (sprites, tell target comand, shapes and many
more features.

SwishPower FX is an add in program(plugin) for FlashMX and cannot be used as a standalone product. Not all swish 2.0/swishmax can be recreated or modified to the extent in PowerFX
they can in Swishzone realized that while many
flash users enjoyed the effects created with swish they did
not wish to purchase swish2.0 or swishmax they simply wanted
the effects.

For a short but more complete list of the differences
between swishmax and swish 2.0
Check out HughB's thread at swishzone.
http://www.swishzone.com/forums/index.php?act=ST&f=20