Compound holes contain several superimposed holes. For example:
-
Compound holes contain two components:
The first component has a length
and diameter 
. This has a Component of First.The second component has a length
and diameter 
. This has a Component of Second or Last. - If you create individual holes you will create two holes:
The first hole has a depth
and diameter .The second hole has a depth
and diameter .
You can see the difference between the representation of a compound hole and an individual hole in the Hole Feature Sets created.
A compound hole can have a Top, Bottom and Component top.
The first component has a Top 
and Bottom 
. This has a Component of First.
The second component has a Top , Component top and Bottom 
. This has a Component of Second.