What is the difference between investment and gambling?

Assalam Alaykum my dear brothers and sisters in Islam. I was recently wondering what is the difference between business investment and gambling in Islam? Since as far as I know investing in businesses is Halal but gambling isn't. Why is that? In investing you invest money and expect a profit which is based upon luck and slightly calculated figures, and gambling is also the same, isn't it? Can anyone explain to me the difference between them from an Islamic perspective? and why one is halal and the other isn't? JazakAllah Khair.