What's the difference between Minoxidil and Rogaine?

There is no significant difference between Rogaine and topical minoxidil. Rogaine is a brand name. Minoxidil is a generic name.

Rogaine is a brand name for minoxidil. Minoxidil can be purchased in varying strengths from 2% to 5% liquid or foam.  Minoxidil can be helpful in male/female pattern hair loss when used consistently and as directed (2 x per day) . It is best used as part of an overall program that attacks the problem from different angles. (Capillus 272)

Rogaine is a popular brand name. The generic drug is called minoxidil. Many companies make minoxidil. Rogaine is the only producer of the foam formulation right now.