I too am wondering the HM definitions. Big/small business versus startup. What is the definition of startup? I don't understand why businesses that go for VC funds have the monopoly on the term "startup".
The definition I've seen given by PG is anything that scales up. In other words, a business that sells a product that can be used by many users. A small business is usually something that offers a service (a restraunt, a barber shop, or a consulting firm).