SOCKET HEAD: This is a head that finishes at the neck in a rounded ball shape, it fits into a matching socket in the body thus allowing the head to turn and move relative to the shoulders.
SHOULDERHEAD or SHOULDER HEAD: This is where a head and shoulders are made in one piece so that there is no movement possible between the head and shoulders. This type of head is usually mounted on a stuffed body made of cloth or kid leather.
FLANGE NECK: The head ends at the bottom of the neck with a flange or rim which allow the head to be inserted into the neck of a cloth body and the fabric sewn tight holding the head in place. The head can often be turned to the side, but has no up/down movement. This is mainly found on baby dolls.
SOLID DOME: This describe a head that has no opening on top - the top of the head is domed or rounded and there is no opening into the head.
BELTON TYPE: This term is used to describe dolls that are solid domed except for two or three holes - it is generally accepted that 2 holes are for the stringing of the doll (they are usually found one on either side of the top of the head) and if there is a third hole (or only one) then this is for attaching the wig (sometimes the wig was made by poking a hank of mohair through this hole, then spreading the hair around and over the head). The top of the Belton Type head may be slightly flattened.
CUT: This describes the way in which a large hole is cut into the head at the back and top allowing the fixing of sleeping eyes. When the cut is fairly horizontal at the top of the head this may be called a German Cut, whereas a French Cut is made much more sloping downwards towards the back of the head. The type of cut a head has can be indicative of the country of origin but this is not a foolproof method of placing a doll.
PATE: This is a domed piece (usually cardboard but sometimes plaster as in the case of Kestner dolls for German dolls, usually cork for early French dolls) that covers the cut out part of the head allowing the wig to sit naturally.
I hope this has made things clearer - if you need more information please contact me. Check out my other guides for more terms explained. Let me know if you'd like a guide for something particular relating to dolls.