Both cabins are upgrades, but they serve different needs.
A wider seat with more recline, a leg rest and footrest, in a smaller cabin.
Business class with lie-flat seats, more privacy and a fuller premium service on long-haul routes.
Comfort+ is the lowest-priced upgrade, mainly adding legroom.
Need help comparing? Call +1-800-984-7414. See the Delta Premium Select vs Comfort+ difference for the lower cabins.