Difference between two models of iPhone 5?

No sense in retyping, even to copy/paste. See here: http://www.iphonefaq.org/archives/972158

Depends where purchased: In the US(and North America), A1428 is the GSM model, & A1429 is the CDMA modle. In Europe, Australia, Japan, etc., the A1429 is the GSM model, A1428 is not sold there. All has to due with LTE & what bands are supported where.

Well, mine is an on-contract A1428 and is running LTE on Telcel's networks....

And it should be, as you're in North America & that's the model you should have.

Well, yeah, geographically speaking. At least Apple's got its GPS coordinates right, since many other companies disdain us as being in "Latin America", entity unknown in all maps and globes.

I am sorry but if you could answer my question specifically: I live in New Zealand which sells the A1428 Iphone 5 however I travel to the US frequently and would want to purchase a A1429 from TMobile and use it when I am in the States. I would buy a SIM card for Vodafone down here in NZ. Are they one and the same? Cheers.....

No... Tmobile is GSM and uses the A1428