Canada is HUGE, so for the Aussie traveler it can be a bit of a hassle to get your head around the time differences.
And with Australia being such a big country as well, the differences are quite substantial even between the East coast vs the West coast (of either Canada or Australia).
So for that reason, if you are at all unsure then the easy way to work it out is to use one of the many time and date calculators. They take the guess work out of it all and help to make sure that you aren't calling people in the middle of the night. This is especially important because daylight hours there are generally our night time hours here in Australia.
Here is a map showing where the time zones are in Canada, but don't forget that if you have trouble knowing just from the image then we suggest that you check out Happy Zebra Time Zones