Coastal and Carpet Python - Difference?

[Bluebonnet Herp]

I've seen some really high yellow with black carpets. What are they called? Does anyone know of a website with a detailed description on carpet pythons?

That's a Jungle Carpet Python, another subspecies with the same fate as Coastals. In fact, Coastals are often mixed with Jungles to achieve high yellow jaguars. Jungle x Coastal are the most common crosses and my understanding is that most carpets are part coastal and jungle. That all aside, you can still find fine specimens of both pure lineage and mixed decent.
Inland Reptile is a great site that provides both comprehensive information on carpets and he specializes in pure specimens that he offers for sale.