a windows service is installed on a Windows box and is very
windws platform dependent. it keeps running in the back
ground even if the user has logged off. a service is
typically use ful where on servers there are long running
processes.

An XML Web service is a component that implements program 
logic and provides functionality for diseparate 
applications. These applications use standard protocols, 
such as HTTP, XML, and SOAP, to access the functionality. 
XML Web services use XML-based messaging to send and 
receive data, which enables heterogeneous applications to 
interoperate with each other. You can use XML Web services 
to integrate applications that are written in different 
programming languages and deployed on different platforms. 
In addition, you can deploy XML Web services within an 
intranet as well as on the Internet. While the Internet 
brings users closer to organizations, XML Web services 
allow organizations to integrate their applications.


A Windows service starts much before any user logs in to 
the system (if it has been setup to start at boot up 
process). A Windows service can also be setup in such a way 
that it requires a user to start it manually ? the ultimate 
customization!
Windows services run as background processes. These 
applications do not have a user interface, which makes them 
ideal for tasks that do not require any user interaction. 
You can install a Windows service on any server or computer 
that is running Windows 2000, Windows XP, or Windows NT. 
You can also specify a Windows service to run in the 
security context of a specific user account that is 
different from the logged on user account or the default 
computer account. For example, you can create a Windows 
service to monitor performance counter data and react to 
threshold values in a database.

Window services is a long running executable application 
with is run in its own window session.Window services have 
the ability to start when the computers boot and it can 
manually handled.We can Manulay start,stop,pause window 
services.


Webservices is a business logic Components which provide 
functionalatily via internet.The funcanality provided by 
Webservice can be used by any application irrespective of 
the progamming langauge,Hardware platform and Operating 
System on it is running.Webservice uses SOAP in ordr to 
Expaose the Business Funcationality to world.