We dont really have a nickname like E town or such each little municipality has there own nickname such as North van and west van, i wouldnt say that downtown vancouver is referred to has gastown, thats just one part of the downtown core, mostly the main area is just downtown, no other nickname, theres also the NOrth shore for west van and north van as they are across the water
We do though have the not offensive, but cultural nicknames that i dont think i can mention here..