please help me figure out which is more risker and why?

Depends on what u mean by investing in the bank. Technically, in order to invest in a bank, u would buy shares of that bank, in which case, the riskier investment would come down to the strength of the individual investments.

If u mean placing ur money in a bank issued investment, such as a CD, savings account, mutual fund or money market fund, these investments would be less risky than investing in shares of a single or handful of companies, for various reasons having to do with diversification & risk.

If you keep your money in an account at the bank. Then it is insured by the government. And you can rely on the government to pay you if the bank goes bankrupt.

But if you buy shares. And the company goes bankrupt. Then you loose everything. And no one will pay you back anything.