What is the difference between Single Logical Table Source and Multiple Logical Table Sources?

Below is the difference between "Single Table Source" and "Multiple Logical Table Sources" in OBIEE
If a logical table in BMM layer has only one table used as a source table then it is called as Single Logical Table Source and in case the logical table in BMM layer has used more than one tables as the source to it then it is called as Multiple Logical Table Sources.

For example -
Fact table has Multiple Logical Table as (in general) sources used in Fact tables come from different - different physical tables.