Hi Parkgate,
The short answer is RealBand can easily create loops while it is more cumbersome to create loops using Band-in-a-Box. RealBand allows you to select individual tracks and track segments to export as a loop while Band-in-a-Box exports complete songs as a loop.
Please see my response and the responses others provided in the earlier thread you started where you asked the same question
+++ HERE +++.