Service Management vs. Capital Asset Management

I'm trying to determine if a business needs to purchase licenses for both Service Management and Capital Asset Management.

The business hires equipment to customers and needs to manage maintenance of that equipment. The business still owns the equipment and will sometimes charge the customer for the maintenance and other times the business wears the cost... depending on the nature of the fault. They also sell equipment to customers and may need to maintain it under warranty (at no charge).

Should this business be using Service Management or Capital Asset Management to manage this maintenance? I would think they would set up a service contract in the Service Management module and then use Service Billing to generate invoices to the customer. However,  please correct me if I'm wrong.