My understanding is that Zulu time is basically the same as GMT. Zulu refers to the GMT time zone. You then "step" alphabetically from time zone to time zone as you get further away from GMT. For example, in the U.S. the time zones are Romeo (Eastern), Sierra (Central), Tango (Mountain), Uniform (Pacific), Victor (Alaska), Whiskey (Hawaii).
Hopefully I'm explaining it correctly!!
- Jen