From my experiences, I'd say that a
production electrician is more similar to a master elec than a head elec. I associate production elec with the building and preparation of a show, and their job is done by opening. They are much more present when there is a shop
build involved, and not so much when it's a
house rig.
This is much of what I'd consider a master elec in
regional theatre, except they are mostly related to the preparation of the
house rig for a given
plot. Again, their responsibilities are much more in the planning and implementation phases, and they are much more hands off once the show opens, but they may be involved in a department-head sort of way.
A head elec is more of a show
call position, I associate them with board opping, but also responsible for the maintence of a show once it is opened. They are the
point person for changes and integrity of the lighting.