What is the difference between a contract for service and a contract of service?

I always get asked this. The easy way to remember this is:

1. Taxi Driver/Customer- Contract for Service.
2. Chauffeur/Employer - Contract of Service.

In general language, the taxi driver one is more commonly termed "independent contractor", whereas the the chauffeur is more often called an "employee".

(You could actually write volumes on where the line between the two is, but this is the most useful way to remember the distinction).