Trucking: trucking, trip lease, expedited services

Question
what is the difference between a courier service and a freight forwarder or broker?  Also, if a motor carrier no longer owns trucks, and uses O/O with their own authority and insurance, do they become a broker?  

Answer
Pat, here is an article that goes into some detail on the subject.
http://www.inboundlogistics.com/articles/fineprint/fineprint0506.shtml
Courier service is generally associated with small parcel and expedited services.  See Wikipedia for a good discussion:
http://en.wikipedia.org/wiki/Courier#USA
Am Owner Operator is simply  someone who leases both their truck and a driver to a licensed carrier.  It can be a simple trip lease or more commonly a longer term exclusive lease.  Hope this helps.