<a href="http://www.t-nation.com/store/products/alpha-male"target=“new”>Alpha Male contains Tribulus terrestris, Vitex, Eurycoma, and Carbolin 19.
<a href="http://www.t-nation.com/store/products/tribex"target=“new”>Tribex contains Tribulus terrestris and Vitex agnus castus.
Alpha Male is the more powerful of the two given it’s two extra ingredients, and therefore it does cost a little more.
You can read about each of those ingredients by clicking the links above.
For serving info, simply follow the label. Some start with a minimal serving then increase to maximal, while others just jump to maximal. It’s up to you.