There are a couple of ways to group Projects that have similar nature. You can certainly create a Portfolio, highlight multiple projects in a Projects module and by using Move button >> move it under that portfolio.
See screenshot: http://screencast.com/t/FhwypAudmB
You can also create a custom field (pick-list type) at a project level with different category values. Then you can easily define category for each project and with filtering in place create different views for each category.
For further information and assistance, I suggest contacting your CSM or attending our free Q&A webinars (http://www.clarizen.com/live-demo.html#second), where our Customer Success Managers can discuss your requirements in detail and suggest best practice advice accordingly.
All the best,