The difference with TestPowder is that you are getting much more than a standard, standalone DAA product:
1g Agmatine- amazing muscle pumps and performance; may also potentially increase LH-RH and LH which in turn, could hypothetically increase testosterone levels
Aframomum Melegueta - used as sexual enhancer or aphrodisiac - may possess strong anti-estrogenic properties as well as invrease serum testosterone levels
L-Carntine Tartrate - shown to increase the expression of the androgen receptor (AR) in skeletal muscle
Trimethylglycine (betaine) - there are data demonstrating that this compound can improve exercise performance and shown to alter anabolic and catabolic hormones in a fashion that is conducive of muscle growth
Gammo-Mangostin - shown to inhibit aromatisation - estrogen synthase inhibitor activity