Attached is a picture of the basic frame work for crown molding including meaning and placement of the following :
Note : Measurements will always reflect an installed piece of crown. ( i.e. How it sits ).
Height : Measurement from the ceiling to the bottom of the crown end.
Projection : Measurement from the wall to the edge of the crown end.
Face : Measurement of the crown molding from top to bottom (Note : do not confuse with how the crown molding will sit as that would be the Height and Projection. ).
Length : Measurement of the entire crown molding stick.