The only difference is the amount of acetaminophen. Hydroco 7.5-500 has 7.5 mg of hydrocodone and 500 mg of acetaminophen. Hydroco 7.5-750 has 7.5 mg of hydrocodone and 750 mg of acetaminophen. Acetaminophen is added to boost the effects of the hydrocodone.
Note: The current maximum single dosage of acetaminophen is 1 gram (1000 mg), however, an FDA advisory panel has recommended lowering it to 650 mg due to the risk of liver damage from high doses of acetaminophen.