Catalan language:

Despite its relative lexical unity, the two dialectal blocks of Catalan (Eastern and Western) show some differences in word choices. Any lexical divergence within any of the two groups can be explained as an archaism. Also, usually Central Catalan acts as an innovative element.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What are the two dialectical groups of Catalan?
Eastern and Western