Record Center vs Document Center
Document Center is like a publishing house. Means that author, review, Edit, approve, manage actives related to document are going on. (Read + Edit operation on documents are going on.)
Record Center is like a Book Library. Means that archiving, classification, record keeping and destruction of documents is going on. (Means Only Read, no Edit operation is going on.)
In real world enterprise, both are needed. First, document management activates are performed in Document center. Later in life cycle of document is sent to Record center for record management activities.
Implementation wise, User submit document to Record center, where based on administrator defined rules for classification and archiving of document is done for Audit and litigation related activities.
Whereas Implementation wise, User from different teams submit document to Document center as collaboration repository for authoring process across different teams.
Ohhhhh, Then Why Document workspace?
Document workspace is for smaller domain in terms of features and no of document being used, as compared to document center.
So suppose that you are writing coding standards as word document for your software house. So you created a document in workspace and started authoring the standards, shared with you team lead. He provided feedback via sharing feature. Once initial version is finalized you published the standard document in Document Center and collaboration started with Project manager, Software Architect, QA Manager, VP Engineering as Review, Edit, approve activities. Once approval from client is done, then Coding standards document is sent to Record Center for book keeping as Company standard for coding. From Record Center anybody can read and implement the same standard across the company.