Lots of good opinions above. Here is what comes to mind for ME when these terms are used.
Leathercraft = leather that has been carved, tooled, stamped, dyed painted, etc.
Leathercrafter does the above.
Leatherwork= harness, shoes,etc. things made from leather without the artistic part.
Leatherworker does the leather work.
Some things can involve both such as saddles holsters etc.