There are some library files loaded as a service but not handled as a full service. To get the full picture, go to the command prompt and type in:
tasklist /svc
Those tasks not loading a service will have N/A listed under services. Some of those listed as a service will not be shown in the service manager because there are no options available for them (eg. SamSs, slsvc, Spooler).
J.A. Coutts