Two similar questions but I don't understand the difference

1.What is the annual tax shield to a firm that has a capital structure consisting of $100 million of debt and $180 million of equity, if the average interest rate on debt is 9%, the return on equity is 13%, and the marginal tax rate is 40%?

2.What is the present value of the tax shield to a firm that has a capital structure consisting of $100 million of perpetual debt and $180 million of equity, if the average interest rate on debt is 9%, the return on equity is 13%, and the marginal tax rate is 40%?