The different Zope application servers focus on content management (CMS) and component architecture (CA).
They evolved over time, using Zope 2 and Zope 3 as the base to build on.
Zope
Zope is a Python-based application server for building secure and highly scalable web applications.
Plone
A powerful, flexible Content Management
solution that is easy to install, use and extend.
Plone lets non-technical people create and maintain information using
only a web browser. Perfect for web sites or intranets, Plone offers
superior security without sacrificing extensibility or ease of use
Silva
Silva is a powerful CMS for organizations that manage multiple or complex websites.
Content is stored in clean and futureproof XML, independent of layout and presentation. Features include versioning,
workflow system, integral visual editor, content reuse, sophisticated access control, multi-site management,
extensive import/export facilities, fine-grained templating, and hi-res image storage and manipulation.
Silva has an open source (BSD) license.
Zope 3
Zope 3 evolved from Zope 2 and improves the development experience through the use of a component architecture.
Grok
Grok is a web application framework for Python developers. It is aimed at both beginners and very experienced web developers. Grok has an emphasis on agile development. Grok is easy and powerful.