The Community Edition (OSS)
The Community Edition is the foundation of all MySQL Workbench editions—versions that are currently available or those that will become available in the future. All editions of MySQL Workbench are based on the Community Edition and all future improvements to the base framework and feature set will be included in this version. The Community Edition is a full feature product that puts a powerful database management tool into the hands of the MySQL community.
The Standard Edition
The Standard Edition is a commercial extension that builds on top of the OSS Edition and adds modules and plugins, allowing for an optimized work flow. The highlights of this edition are:
MySQL Specific Schema Validation
Model Validation
General Schema Validation
DBDoc
DBDoc provides the following features:
Document complex database schemata
Document all SQL object types
Document output available in different file formats
A comparison of edition features can be found at MySQL Workbench Developer Central.