Businesses such as Zipcar and Enterprise Car Club provide a fleet-based service, meaning the company owns and maintains the vehicles. Often the company will include things like fuel, tax, insurance (the list goes on) - but it depends on the brand.
Whereas, peer to peer services (Turo, Hiyacar, getaround) are based on car owners adding their cars to the platform and charge a fee for members to rent them.
For more information go to CoMo UK.