ASP.NET MVC 1:
a. The default view engine is WebFormViewEngine
b. Model-View-Controller design pattern
c. Action and Result filters
d. Runs on .NET 3.5 and with Visual Studio 2008 & Visual Studio 2008 SP1
e. Routing
f. Unit testing
g. HTML helpers
h. AJAX helpers

ASP.NET MVC 2:
a. Runs on .Net 3.5, 4.0 and with Visual Studio 2008 & 2010
b. Client-side validation
c. UI helpers with automatic scaffolding & customizable templates
d. Attribute-based model validation on both client and server

ASP.NET MVC 3:
a. Runs on .Net 4.0 and with Visual Studio 2010
b. The Razor view engine
c. ViewBag dynamic property for passing data from controller to view
d. Global Action Filters
e. Better JavaScript support with unobtrusive JavaScript, jQuery Validation, and JSON binding
f. Good Intellisense support for Razor into Visual Studio

ASP.NET MVC 4:
a. Runs on .Net 4.0, 4.5 and with Visual Studio 2010SP1 & Visual Studio 2012
b. ASP.NET Web API
c. Bundling and minification
d. Mobile project template using jQuery Mobile
e. Support for the Windows Azure SDK

ASP.NET MVC 5:
a. Runs on .NET 4.5, 4.5.1 and with Visual Studio 2013
b. One Asp.Net
c. Asp.Net Identity
d. ASP.NET Scaffolding
e. Authentication filters - run prior to authorization filters in the ASP.NET MVC pipeline
f. Bootstrap in the MVC template
g. ASP.NET Web API2