Both these preparations contain a narcotic analgesic and acetaminophen (a mild non-narcotic analgesic). Of the narcotic analgesics, oxycodone is considered slightly more potent than hydrocodone. Note that Lortab 10 contains more acetaminophen than Percocet 10.
A Percocet 10 can contain 650MG of Acetaminophen also. Either way, Percocet's are better that Lortabs. I'd say a Lortab 10 compares to a Percocet 5. That's why Percocets are Schedule II drugs and Lortabs are Schedule III.