The main difference relates to block sizes. Generally in East Cannington, the blocks are larger (due to a lower zoning) so the homes are generally larger. Cannington has more strata type units & villas, as the zoning is higher, many of the older & larger blocks have been redeveloped and new units built.
As of October 31st 2013, the median price for Homes in Cannington is $448k, with units being $423k, in East Cannington the median price for homes is $525k and the units being $440k.
Another of the main differences, possibly - is that there is more air craft noise in Cannington, than East Cannington (being slightly more direct in the flight path)
Also, there are some parts of Cannington surrounded by heavy/light commercial, where as in East Cannington it is mainly (approx 90% or more) residential. So you would be more likely to be surrounded by other residential homs/estate type living in the newer developements.
If you would like I can set you up to receive Market Reports monthly for Cannington or East Cannington for free :)