Help in Currency Exchange Equation

While revising I got completely confused with 2 equations : The currency forward equation in econ is: [So *(1+ip*D/360)/(1+ib*D/360)]

The equation to compute a forward rate in derivates is So*((1+Domestic Rate)^t/(1+Foreign rate)^t)

Why are the equations different ? Arent they both solving for the forward price? Thanks!

The Econ equation assumes that the risk-free rates are nominal rates.

The Derivatives equation assumes that the risk-free rates are effective rates.