What is difference between these 2 version of JSF (JSF 1.0 and JSF 2.0)? As I am new to java, I only find that difference is at Architectural level. But, in perspective, I can't get how much it affects the application development ?
Also, the MVC imposed is different with JSF and Spring. Even if JSF has improved architecture, still Spring is much more in use. What is the importance of Spring with above point ?
JSF 1.0 was the first release of the JSF specification (JSR127 FR1), released around March 2004. It was pretty buggy and shortcoming and it was improved shortly thereafter with JSF 1.1 (JSR127 FR2) around May 2004. It was later succeeded by JSF 1.2 (JSR252) around May 2006 wherein mainly the EL and the view handling was improved and unified so that it's not tight-coupled to JSP anymore.
JSF 2.0 is the second major release of the JSF specification (JSR314), released around July 2009. Major improvements cover the use of annotations, parameterized types (generics), support for GET requests, ajaxical powers, new view scope and ability of defining custom scopes, resource handling and the inclusion of Facelets as default view technology (instead of the legacy JSP).
Also see What's new in JSF 2?
As to which one to choose, just pick the latest. It'll be better. It's the same as asking if you should choose Java 1.0 or Java 1.6.
As to the Spring part, it's just an IoC framework. You can do as good without it. You can eventually go for EJB and/or CDI.