While the fundamentals remain the same, there were changes in the product over time that have affected the inter and extra-server communications paths. SharePoint 2010 introduced the Service Application model with Windows Communication Foundation proxies and endpoints. SharePoint 2013 brings additional core-building blocks to the product such as Distributed Cache or optional components such as Office Web Apps Server and Workflow Manager with an underlying Service Bus.
These components publish some sort of endpoint to communicate with SharePoint 2013 on different ports. You should not forget to secure communication with these external endpoints with a SSL certificate. SharePoint 2013 uses oAuth for Server to Server (S2S) communication and you absolutely don’t want oAuth bearer tokens flying over your network in clear text. They contain sensitive information and any party in possession of a bearer token can use it to get access to the associated resource. You can find more information in The OAuth 2.0 Authorization Framework: Bearer Token Usage RFC 6750 document. Yes, this means you should have SSL certificates deployed on your SharePoint sites as well.