I'm sorry, I didn't realise that you didn't know the technical names for the parts of an aircraft. Nacelle, whilst being a French word, is the accepted term for the "bit around the engine".
You asked what was your silly question - well parlez vous en Anglais was the silly question. Come on - I tried to help you but if you're just going to be sarcastic, why should anyone bother? Anyway, as you will note, 2 can play that game.
One little tip I discovered quite by accident - to tell the difference between a 737NG and a Classic (you may have to look that up), the strobes (the flashy light thingies) on an NG are co-ordinated so all flash at once. On the classics, they don't. Helpful when trying to identify a -700 or a -300.
Splitting an A318 from an A319 is a pain unless they're parked together. One little detail is that around the NLG doors (that's the door above the front wheel if we have to be basic) there are 2 strakes (little bits of sticky out metal that are quite long) - presumably for stability - that the A319 doesn't have. The A318s fin is a bit taller (the fin is the tall bit at the back of the plane) than the A319 but unless they're parked side by side then you won't really see it. The A318s rudder (does that need an explanation?) doesn't go all the way to the top of the fin but the A319s does.