So here's the problem- there's no standard definition on each of these and since different groups of people mixed up the definitions of these and then some vendor sauce was poured over it, things start getting blurry.
Let's go back to the basics:
- facade - a facade is a component that makes a component appear as something else;
- wrapper - a wrapper (or better: wrapper service) is a service that wraps a service or system and makes it appear as something else;
- mediation - a mediation is a component that makes a component appear as something else.
- contract from evolving service logic -or-
- service logic from evolving back end systems -or-
- offer multiple contracts for the same logic -or-
- offer a standardized contract for a non-standardized component -etc.
A wrapper service is a service wrapping another service or system. The service architecture (the infrastructure inside a service) can actually contain (a) facade component(s) to make its magic work. Many services are -if you looked at them conceptually- wrapper services. Ie. an entity service exposing a standardized contract can contain a core service logic component to access a database to access but it would typically also contain a facade component to make that database access logic appear as something more usable from standardized-service-contract point of view. Also application-specific public service which are there to accommodate for service consumers that cannot adhere to our standardized service contract are considered wrapper services. Ideally this kind of a service would wrap the standardized service and make it appear in a way that the domain specific service consumer can understand.