One coat doing two jobs
Cure and seal is a liquid product, sprayed or rolled onto a slab right after finishing, that is built to do two things with a single application. In the first days after the pour, the film it leaves behind slows how fast moisture escapes the surface, which is the same job a plain curing compound does. Once curing is finished, that same film keeps sitting there and works as a light surface sealer, cutting down on staining and giving the surface some sheen. A plain curing compound, by contrast, is only built for that first job and is meant to break down or wear off once curing is done, with a separate sealer applied later if the slab needs one.
Where it earns its keep
Not every slab needs a sealer right away, and cure and seal is not automatically the right call just because it is available. It earns its keep most on surfaces that see the most exposure or the most eyes, stamped and decorative work, colored concrete, anything where staining resistance and a bit of sheen matter from day one. A broom finished driveway or a plain walkway can often go without any sealer at all and hold up fine for years, and putting one on a surface that did not need it is money spent without much to show for it.
What it trades off against a two-step approach
The convenience of one product doing two jobs comes with a tradeoff. The film a cure and seal product leaves is generally lighter and shorter lived than what you get from a dedicated curing compound followed weeks later, once the slab has fully cured, by a proper penetrating sealer applied on its own. On surfaces that see steady traffic or a lot of weather, that lighter film wears thin faster and may need recoating sooner than a true two-step system would. There is also a look to consider. Some cure and seal products leave a slight sheen that some owners like and others would rather not see on a plain broom finished driveway. Which approach fits a given job comes down to the finish, how the surface will be used, and how much upkeep the owner wants to sign up for down the road.