Terms suggested for receivers of services include: service-users, clients and patients. None of these are particularly satisfactory with "client" most accurately reflecting the monetary relationship entered into in the USA between the person receiving services and the person supplying them. A simpler suggested term is "person in distress" or, in the plural, "people in distress." The abbreviation is PiD.
The only term suggested so far for suppliers of services is "professional." There are cases to be made for using "service-provider" or "label-enforcer" or "code-enforcer." The best term in this context would seem to be "professional." The opposite of "professional" is, in this context, "client."
In the UK one suggestion is to call both the people providing the service and the people using the service "service-person," which promotes a sense of inclusiveness.