Jiggers (pl. noun) are mechanized arms which bring a mounted profile template down on a centered ball of clay that is spinning on a wheel-mounted mold. Jiggering (verb) is used to make identical items such as plates and shallow bowls quickly.
A jolley (noun) is very, very similar to a jigger. The only difference is that with a jolley, the clay is molded within the mold, rather than over the mold. Jolleying (verb) is used to make cups and deep bowls.
Studio potters rarely use jiggers or jolleys. These are generally seen in factories or in pottery production shops.
The shop worker set up the jigger to do plates. (noun)
Jiggering bowls takes very little time. (verb)
This jolley was set up to do flower pots. (noun)
He was jolleying the cups as quickly as possible.