Clients and contacts in WorkGuru are the customers you do work for on projects and stock sales. Though not mandatory, the client is generally the company, and the contacts are the people who work at the company. There is no issue with making a client a person if you have a business to client (B2C) workflow.
Clients allow you to capture standard address and contact information as well as WorkGuru specific information such as pricing tier and currency etc. The client detail page will also display full history of any interaction with that client to date.
Clients in WorkGuru will be created in the connected accounting system when invoiced so there is no double entry required.