I believe a planner, is just that, someone who will plan the whole thing for you.
Not sure about consultant.
Coordinator is someone you hire to help with the flow of events, interact with vendors, and basically take care of everything the day (and sometimes week) of.
A recent bride over on theknot used CLM weddings and was thrilled with how it went.
I personally prefer to plan everything myself and hope to enlist a couple of friends to be my "go to" people on the day itself.