1. A device implementable in a website design program, said device comprising: a component based version comparer to compare at least two versions of a website, said at least two versions having components in a set of hierarchies, wherein said components are at least one of a visual component, a container and a non-visual site element, and to generate a difference tree representing the differences in said components between said at least two versions of the same website, wherein said version comparer preprocesses said components in each single version of said at least two versions of said website to determine at least one of internal geometric, semantic, content and attribute relationships before comparing said components and said relationships between said at least two versions of said website using at least one of semantic, geometrical, content and attribute analysis; and a version merger to create an integrated version of said two versions of said website based on said difference tree.