It's the difference in preference between e.g. $500k nearly sure profit versus a tiny chance of $100M profit but a most likely result of losing it all. For a "normal" business, the first one is preferable; a startup is the condition where the first result is considered unacceptable and the investors are there for the second possibility only - go big or go home.

It means quite different cultures, quite different "correct answers" to similar situations, and has mostly opposite requirements for many business factors and people involved.