some of the varients we have in Australia of the same aircraft type have different door layouts. The example I'm thinking of is the 767-338 which has one main forward door and then two overwing exits, and the 767-336 which has two main forward doors and one larger overwing exit.
To answer a question from well before. Australia does get 777's but none of our own airlines have them. Most of the 777's seen in Australia come from Southeast Asia, New Zealand or Europe/asia, but none from the local airlines.
Nowadays I find the usual airliners easy to identify... it's the GA I have issues with. I mean I can tell a Cessna 172 and a Cessna 152, or a Piper Chrokee to a Tomahawlk... Cirruis SR22, C182, C177, Baron B58, and so on, but it's when you see something you have never seen before and you go "what is... that?"
Texan T-Bird was one of the one's I only reicently discovered, and there's a bunch of anphibians I walk past to get to my flight school's C172's which I can't Identify either. Robinson R22 and R44 are easy, favourite is the Aerospaciale Dauphin II and similar as far as helos go... There's still a whole bunch of planes down at the local GAAP though that I can't tell you what they are.