Suppliers and Contacts in WorkGuru are the suppliers you purchase goods and services from. Though not mandatory - the supplier is generally the company, while the contacts are the people who work at the company. There is no issue with making a supplier a person if required.
Suppliers allow you to capture standard address and contact information as well as WorkGuru specific information such as pricing tier, lead days and currency etc. The Supplier Details page will also display full history of any interaction with that supplier to date.
(Note: you can only have one email listed in the email box, using the contacts section for any extra business emails that a supplier may use)
The Supplier in WorkGuru will be created in the connected accounting system when they are invoiced, meaning there is no double entry required.