Hi slind
There's more than two types of testosterone. I take it you're alluding to the close similarities between the Enanthate and Cypionate compounds? Stormshadow pretty much hits the nail on the head...
They are chemically and structually very similar. Cypionate has a carbon molecule more than the enanthate compound, but in effects and strength and so on they're very much alike.
Some of the difference is due to licensing and availability too. I think Testosterone Enanthate is more common in the UK and Europe, while Testosterone Cypionate is prescribed more for TRT in the United States.
Having said the above, don't forget that we're discussing "Testosterone" cypionate and enanthate, and they're not to be confused with other drugs with the name:
Masteron (Drostanalone Cypionate or Enanthate).
Tren. (Trenbalone Acetate or Enanthate).
Craig