What is the Different between Struts 1.x and Struts 2.x

Struts 1.x	Struts 2.x
In struts 1.x front controller is ActionServlet	In 2.x front controller is FilterDispatcher
In struts 1.x we have RequestProcessor class	In 2.x we have Interceptors instead RequestProcessor
In struts 1.x we have multiple tag libraries like, html, logic, bean..etc	In 2.x we do not have multiple libraries, instead we have single library which includes all tags
In struts 1.x the configuration file name can be [any name].xml and we used to place in web-inf folder	In 2.x the configuration file must be struts.xml only and this must be in classes folder
In struts 1.x we have form beans and Action classes separately	In 2.x form bean, Action classes are combinedly given as Action class only
In struts 1.x properties file must be configured in struts-config.xml	But in 2.x we need to configure our resource bundle(s) in struts.properties file
In struts 1.x we have programmatic and declarative validations only	In 2.x we have annotations support too along with programmatic and declarative validations

Functional Differences.

In struts 1.x declarative validations are done by using validation frame work	In 2.x, declarative validations are done by using xwork2 frame work by webwork the reason being, its support valuations through Annotations
·         In struts 1.x an Action class is a single ton class, so Action class object is not a thread safe, as a programmer we need to make it as thread safe by applying synchronization	o    In 2.x an Action class object will be created for each request, so it is by default thread safe, so we no need to take care about safety issues here
In struts 1.x we have only jsp as a view technology	In 2.x we have support of multiple view technologies like velocity, Free marker, jasper reports, jsp, etc
In struts 1.x Action class is having servlet dependency, because in execute() method accepts req, res parameter right	In 2.x Action class doesn’t have any servlet dependency, because its execute() method doesn’t accepts any parameters, however we can access all servlet objects with dependency injection