I would like to know the difference between the terms - SharePoint Webservices, Server Side Object Model, Client side Object Model(CSOM), REST(oData),JSOM in Microsoft SharePoint.And would like to know which all terms comes under in each of the items.
Your question will lead in link only answers as the terms you specified are too broad.
SharePoint Web Service:
Windows SharePoint Services Web services provide methods that you can use to work remotely with a deployment of Windows SharePoint Services
SharePoint Object Model:
Server Object Model is the most extensive API set available for SharePoint 2013. The core assembly is Microsoft.SharePoint.dll which is installed in the Global Assembly Cache.
The Server Object Model will be executed in the server side & it provides rich set of classes in representing & manipulating SharePoint objects.
Reference Link: SharePoint Object Model Hierarchy
Client Object Model:
Client Object Model provides API to access SharePoint objects from a client machine. The core assembly involved is
For example: You can access & modify SharePoint objects from a remote client machine.
Read more here: Using the Client Object Model
The client-side object model (CSOM) provides client-side applications with access to a subset of the SharePoint Foundation server object model, including core objects such as site collections, sites, lists, and list items. As described in Data Access for Client Applications, the CSOM actually consists of three distinct APIs—the ECMAScript object model, the Silverlight client object model, and the .NET managed client object model—that target distinct client platforms.