Hip measurement is taken around hips and the measurement tape is put to your skin. This is the actual hips circumference.
Full hip measurement is measured taking into account belly protuberance and is always more than hip measurement. You can take the full hip measurement while holding something vertically next to your tummy (e.g. a ruler) and measuring at the same level as you would when measuring hips, around the buttocks and hips and than to the ruler, which means you take the measurement tape off your skin and it passes around the ruler in the air.