Having once been a spotter

really does help....I'd actually be quite embarrased I think to have to ask what another type looks like.
What Flying Boat mentions is actually quite a serious point IMHO -you really should know your Boeings from your Airbuses if you're flying from/into places where you're going to come across them
(Air Traffic are not an aircraft recognition service!)
OK, anorak on, AerBabe - did you know there is a Caravan 1 and a Caravan 2? - and that they are quite different aeroplanes