When looking at the pSemi PE42553 SPDT RF Switch, you may see the part number with a “A” or “B” Suffix, such PE42553B-Z. The datasheet does not call out a meaning for these 2 suffixes.
The meaning of these 2 suffixes is the manufacturing location only
Here is the ordering information in the datasheet
Applicable part numbers
PE42553B-Z
1046-1137-2-ND
1046-1137-1-ND
1046-1137-6-ND