Recessive leathers and american smoothies are not the same. One is codominant, and the other is recessive. They look similar as far as smoothness, but recessive leathers only have a smooth torso. The rest of the body has regular spiney scales.

codominant leathers:
1)Italian leatherbacks(allessandros line)
2)American leatherback(AC reptiles line), aka: american smoothie
* both of these lines will produce silkbacks and are compatible

recessive leatherback:
1)"Skeletor" line

Josh