Basically both have the same principles, their movements are influenced by supply and demand, and the public can predict the direction of price movements with technical analysis methods (see charts and patterns of past price movements) or fundamentals (see intrinsic value or situation and conditions of the company). But still no one can guarantee that the prediction will be 100% correct.
I would prefer bitcoin because it is 5-7 times more volatile than the stock market, although it is very risky but the potential profits are huge.