It would be easy to answer this in a "Lean Startup vs. Agile vs. Design Thinking" format, but it would give the wrong idea. Lean Startup may obviate the need for certain portions of one or the other, but the goals and much of processes are not incompatible with one another. As defined in Lean Startup, a startup is a human institution designed to create a new product or service under conditions of extreme uncertainty. It is the condition of uncertainty that Lean Startup seeks to resolve. Once a customer has been identified and value defined, you'll have conditions wherein production can proceed with reasonable certainty and confidence of success. What that course of action looks like or is called is less important than the fact that the team can now deliver a focused product, with a ready customer. That's a far better culture to work within.