The biggest difference is stock have real companies behind them that already generating revenue and you own the company proportionally to the amount of shares you have while in crypto you invest in an idea that something will become big in the future and you don't own the project, you only buy coin that can be used in the project ecosystem.
The stock is fully compliant with the law. It is very different with the crypto asset which can be considered as a new thing or revolution in the economic system.
The volatility of the stock market based on the performance of the company itself but in crypto, any important thing can give an impact such as the domination of bitcoin, bad news, the development progress and any other things.