Treasury Bills also known as (T-Bills) have low-risk, short-term government instrument (more like government borrowing your money 1 year) that offer fixed, tax-exempt returns, ideal for capital preservation.

While stocks also known (shares) means when you buy it you own part of that  company. They have higher-risk, long-term capital investments that offer potential for higher returns when your capital appreciates and some pay dividends (they pay you some money from their profit, like they are thanking you for trusting them with your money for business).