A friend of mine and I have been discussing why a company should hire a freelancer versus an established consultancy. Other than cost, what are the advantages and disadvantages to hiring a freelancer or consultant?
Hire them to do WHAT?
Just like a client, to leave the description of work vague and ambiguous. 
I kid, I kid!
Thanks box. To add to my questions: what type of jobs would a client hire a freelancer for over a consultancy?
I was asking for you to narrow your question and you made it broader and added a layer of questions.
If you were hiring anyone, I would want to be hired on an hourly basis…
I’d say…
Freelancer: depth of experience
One specific subtask, one individual to manage. Good for tactical needs. Requires more management.
Consultancy: breadth of experience
Entire programs requiring many disciplines and individuals. Consultants employ a range of specialists which can add value from time to time on the project. Good for strategic needs. Requires less management.