Definition:
Lean Canvas is an adaptation of Business Model Canvas by Alexander Osterwalder that Ash Maurya created within the Lean Startup spirit (Fast, concise and Effective startup).
Lean Canvas guarantees an actionable and entrepreneur-focused business plan. It focuses on issues, solutions, key metrics and competitive benefits. The structure is similar to the well-known Business Model Canvas, however some sections are exchanged.
Further Reading:
Book: Running Lean by Ash Maurya.