What's the difference between flutamide and finasteride?

Different drugs. Flutamide is a drug to treat prostate cancer by blocking male hormones. Finasteride is used to treat benign prostate conditions such as BPH (benign enlargement of the prostate). These 2 medications are not interchangeable.
Rx cancer vs Rx BPH. Flutamide is an antiandrogen drug to treat prostate cancer. Blocks testosterone from stimulating the prostate cancer cells to grow. Finasteride is a synthetic 5?-reductase inhibitor, blocks conversion of testosterone to dihydrotestestosterone to decrease bph.