Needles & sizes can be very confusing so I will try to set everything out & explain so there is less confusion.  The size (or thickness) of the needle is sometimes given in one of 2 ways.  As something similar to a dress size EG: 9, 10 , 11, 12, 14, 16, 18, 20.  Or 65, 70, 75 etc

This is a comparison:

9/65, 10/70, 11/75, 12/80, 14/90, 16/100, 18/110, 20/125

9 or 65 being a very fine needle used for georgette, or very fine fabrics 11 to 14 being for cotton quilting fabrics (a 14 if there are several layers)  and anything higher than a 14 up to a 20 is for very heavy or many layers of fabric.