What is the difference between centralized and distributed workflows?
Centralized means you directly checkin to a repository (repo) that is located in a central server, typically on-premises:
Subversion, TFS, Perforce are typical examples of the centralized workflow. Plastic can be used like this too.
Distributed means you always checkin to a local repo in your machine, then push your changes to a remote repo on a server:
Please see here for more Information.