Many people believe that Polished Concrete is a Grind and Seal, contrary to popular belief they are two different methods of concrete floor refinishing. The main difference between sealed concrete and a true polished concrete slab is the densifiers added to a polished floor to strengthen its durability, polishing capability and lifespan.
A sealed concrete floor is only protected with a coating system, whereas a mechanical polished concrete floor has special chemicals added to the floor to harden the cement paste and provide a tight surface to be polished.
When done correctly polished concrete floors will last a lifetime with proper care. The only maintenance required with polished concrete is a rebuff every 10 or so years if it has dulled. The rebuffing will bring back the gloss in the floor
As a sealed concrete floor is coating applied over the top of the concrete it can scratch and damage more easily. Sealed concrete will require recoating every 3 to 5 years depending on traffic and sealer product used.
Polishied concrete, on the other hand, uses chemical hardeners that have been added to the floor making them highly scratch resistant.
Generally speaking, a true polished concrete floor can cost around double the price as a grind a seal but is a more cost-effective flooring solution in the long run as it never requires a recoating.