If you own a business, you normally have high stake on it, meaning you are putting a big chunk of your money and time in managing and operating it. Investment on the other hand can be simply putting your money in one or more businesses or assets that do not require you to have so much involvement in its operation.
Owning and operating a business comes with high risk due to the money and time you need to spend on it. It can make you poor if your business fails but it can also make you very rich if it succeeds. Owning and running a business is often high risk which is why the reward is also high if you succeed but the loss is also steep if you fail.
Investment can be low or high risk depending on what you choose and your knowledge about it. The stock market can be low risk or high risk depending on the strategy that you’re following. Generally, being a business owner forces you to take high risk while being an investor allows you to choose the level of risk you want to take.