ONLY iPads with 3G + WiFi have inbuilt GPS. While the GPS uses info from 3G phone towers to assist locate itself, I can vouch that with no 3G coverage it works beaut for either Hema or VMS, I know because I've got both and have used both out bush with not a 3G signal for miles (and WITHOUT the dongle).
IMHO, I like the display of HEMA better, but VMS will calculate a route for you, and I haven't found this function yet on HEMA but I haven't looked too hard either.
If you have a WiFi only iPad, one can buy GPS dongles (BadElf) for $100. They do work on a 3G +WiFi iPad and I use one because the machine I drive has electrically heated wind screens, which interfere with the iPad's native GPS reception, whereas the dongle doesn't have any issues. I don't know if the dongle works on WiFi only models.