What is the major difference between an open circulatory system and a closed circulatory system? see section 33.1 (page 621) ?

I don't know if this is the answer you're looking for, but an open system is defined as a "system in exchange of matter with its environment, presenting import and export, building-up and breaking-down of its material components." Closed systems, on the other hand, are held to be isolated from their environment.

An open circulatory system is when blood and oxygen do not run through veins, an example would be a crab or earthworm. A closed circulatory system is when blood and oxygen flow through veins, humans and dogs being an example.