Hemp is Cannabis, so both industrial hemp (iHemp) and marijuana are from the same family, just different varieties.
In New Zealand cannabis is illegal, except iHemp which can be grown legally if you have a current licence issued by Ministry of Health.
iHemp is hemp with a THC content less than 0.35%. Nearly all countries in the world allow industrial hemp and a growing number of countries allow medicinal cannabis and recreational cannabis with higher THC contents.
Hemp is a herbaceous annual plant that produces a nut and is related to hops, it produces leaf, roots, seed and the stems are split into fibre and hurd/shiv.
It can grow to maturity in 90-120 days and produces a seed, fibre or dual (both) crop. It requires little if any pesticides, fungicides and herbicides and can actually clean and condition the soil.
The hemp plant is Cannabis Sativa, belonging to the family Cannabaceae of the nettle order (Urticales)
There are many varieties depending on use and are mainly dioecious (distinct male and female plants) but can be monoecious (male and female on the same plant)