Using customers and vendors let you create and follow invoices for each of them. In the case of customers, you receive the payment and in the case of vendors, you pay the invoice.
This approach let you also enter taxes
that you pay in a expense account or the taxes you collect in a income account
. These account are then visible in the reports
Careful, customer, vendor and invoice creation are not reversible, it is better to practice on a test file if you're new and you are not sure of your shot.