Treasury Bonds vs. Corporate Bonds
Corporate bonds are more volatile than treasury bonds.
Interest from treasury bonds is exempt from state and local taxes, while interest from corporate debt is not.
Compared to corporate bonds, a traditional 60/40 portfolio using treasury bonds has historically resulted in higher returns, lower volatility, higher risk-adjusted returns (Sharpe), and smaller drawdowns.
Many investors incidentally hold corporate bonds simply because of the convenience, popularity, and availability of total bond market funds.
Treasury bonds should be preferable to corporate bonds in a diversified portfolio, and have the added benefit of allowing you to avoid the state and local taxes, credit risk, and liquidity risk of corporate debt.