First, the issuers are different.
The issuer of national debt is the country, while the issuer of time deposits is banks or other financial institutions.
Second, profitability.
The yield of treasury bonds is usually higher than that of time deposits, because the issuer of treasury bonds is the state, with high credit rating and low risk. The rate of return on time deposits is relatively low.
Third, liquidity.
Treasury bonds can usually be bought and sold in the market and have good liquidity. The liquidity of time deposits is poor.