Services in Axigen refer to those components that clients can access, request and use information. Clients connect to service using an IP:PORT combination.
On the other hand, modules refer to those Axigen components that also provide services for the clients. However, these components are not accessed using an IP:PORT combination.
Take for example the SMTP module which includes the SMTP Receiving and SMTP Sending services. The SMTP Receiving service can be accessed using an IP:PORT combination so that clients can connect to this service and interact with it, while the SMTP Sending service is responsible for sending messages, meaning that Axigen will become the one connecting to another mail server using an IP:PORT combination.