I don't know what is the difference between a SOAP and REST services.
The
WebServicesFaq points to introductory material on both WS styles.
SOAP would be better to use since you may later choose to send attachment in response which is not possible in case of rest.
I disagree. There's nothing in the problem statement that indicates that attachments may be needed, and furthermore, there are RESTful alternatives that can serve as full substitutes for attachments; so this seems an unnecessary architectural choice.