Yes, they are. The only real difference is the name on the barrel. The Army Special wasn't getting any military sales but was popular with police agencies so Colt made the change to reflect that.
In equal condition the Official Police tends be be more expensive to buy but not necessarily by a lot. It's just better known. The Army Special was available in .41 caliber which was dropped with the change to the Official Police. Also beware of the occasional Army Specials on the market that have been re-barreled with Official Police barrels.