Basically, the Federal law was modeled from the NJ law, except for a few changes. The biggest being that almost everything was grandfathered-in. New Jersey did not do that in 1990.
---In simple terms, anything that is Federally legal post-ban, is legal in NJ, for now.---
The Federal law reads:
§ 921(a)(30) The term 'semiautomatic assault weapon' means:
(A) any of the firearms, or copies or duplicates of the firearms in any caliber, known as -
(i) Norinco, Mitchell, and Poly Technologies Avtomat Kalashnikovs (all models);
(ii) Action Arms Israeli Military Industries UZI and Galil
(iii) Beretta Ar70 (SC70);
(iv) Colt AR-15; (v) Fabrique National FN/FAL, FN/LAR, and FNC;
(vi) SWD M-10, M-11, M-11/9, and M-12;
(vii) Steyr AUG
(viii) INTRATEC TEC-9, TEC DC-9, and TEC-22; and
(ix) revolving cylinder shotguns, such as (or similar to) the Street Sweeper and Striker 12;
(B) a semiautomatic rifle that has an ability to accept a detachable magazine and has at least 2 of -
(i) a folding or telescopic stock;
(ii) a pistol grip that protrudes conspicuously beneath the action of the weapon;
(iii) a bayonet mount;
(iv) a flash suppressor or threaded barrel designed to accommodate a flash suppressor; and
(v) a grenade launcher;
(C) a semiautomatic pistol that has ability to accept a detachable magazine and has at least 2 of -
(i) an ammunition magazine that attaches to the pistol outside of the pistol grip;
(ii) a threaded barrel capable of accepting a barrel extender, flash suppressor, forward handgrip, or silencer;
(iii) a shroud that is attached to, or partially or completely encircles, the barrel and that permits the shooter to hold the firearm with the nontrigger hand without being burned;
(iv) a manufactured weight of 50 ounces or more when the pistol is unloaded ; and
(v) a semiautomatic version of an automatic firearm; and
(D) a semiautomatic shotgun that has at least 2 of -
(i) a folding or telescoping stock;
(ii) a pistol grip that protrudes conspicuously beneath the action of the weapon;
(iii) a fixed magazine capacity in excess of 5 rounds; and
(iv) an ability to accept a detachable magazine.
As you can see from the above, AKs are banned. The substantially identical portion of the NJ law addressed this after the lawsuit, which ultimately set the guidelines for what is legal, both Federally and in New Jersey.
See: http://www.njsp.org/about/fire_ag2.html