Originally Posted by DomesticGoddess

I think you're confusing two very different things.

Airpoints is the Air New Zealand frequent flyer programme, which is (effectively) free to join. When you join you start off at Jade level, which doesn't give you any benefits in terms of additional baggage allowance. By crediting flights to this programme you can earn Silver, Gold and Elite status. Each status level gives a range of benefits, with Gold and Elite being equivalent to Star Alliance Gold.

Koru is a paid scheme that gives members access to Air NZ (and some partner) lounges, but is not Star Alliance Gold status. You still have to earn that through the Airpoints progamme. Koru membership (in addition to lounge access) also gives members additional baggage allowance, and access to some additional preferred seating.