Glider -
Welllll - We'll have to get into some nomenclatural stuff here, but I'm an educator at heart!
When you call something "Sarracenia x wrigleyana," this refers to ANY hybrid cross between a Sarracenia leucophylla and a Sarracenia psittacina. Take pollen from a leucophylla and use it to pollinate a psittacina flower, OR pollen from a psittacina and use it to pollinate a leucophylla flower, and all the offspring would be considered Sarracenia x wrigleyana, no matter how different they look!
BTW - the 'x' in the middle of the name simply means 'hybrid,' so you could say that this name means "the Sarracenia hybrid named wrigleyana."
Sarracenia 'Scarlet Belle' is a specific clone of Sarracenia x wrigleyana. ALL the 'Scarlet Belle' plants that you find out there are from the exact same parent plant, and they have been produced in bulk by tissue culture labs. Sometimes people find unique plants in nature and name them (this is the case with Sarracenia 'Leah Wilkerson,' a named variety of a naturally growing hybrid between S. flava and S. leucophylla). Sometimes people create manmade hybrids, and select the nicest of them to develop into named varieties (like S. 'Judith Hindle' or S. 'Dixie Lace').
I hope this helped. I guess you could say that Sarracenia 'Scarlet Belle' is a Sarracenia x wrigleyana, but not all Sarracenia x wrigleyanas are Sarracenia 'Scarlet Belles'!!!