I can imagine that the 'server' can be a machine/host but can be also a program like ftp server, smtp server, etc.. The 'service' on the other hand refers mainly to applications/programms..
Why can then for example the Sql Server cannot be called as Sql Service? It has the same semanthics. Or the other way round: MS Azure service: why it isn't called Azure Server? :)
I would say:
server is expected to give a responseservice is notAdditionally, a service may include more than a server - it may well be an environment, hardware, SLA and more.
A server is a (possibly virtualized) piece of equipment that can be used to provide a service.
A service is something that you can use (usually remotely) that is provided by one or more servers.
The other difference is that these are really concepts at different levels of abstraction. Servers are concrete things. Services are abstract. Yet people mostly use services, and don't really care about what servers are used to implement them. Do you care about what servers are used to provide Google's web search service? No, you don't. Do you care about what servers are used to provide Amazon's cloud service? No, you don't.
A server is a a software program, or the computer on which that program runs, that provides a specific kind of service to client software running on the same computer or other computers on a network.
Per Microsoft - Windows Azure: operating system as an online service. SQL Server is a Server, Any Stored Procedures or functions you write are Services. (A Query is a dynamic Service that has a life of just the call, it is sent to the Database, compiled, The Server executes the compiled code and returns the results)