You can build and install the community edition, store data and run computations. But you will be limited in a few ways. Here's a summary: http://paradigm4.jlmarketingnh.com/try_scidb/compare-editions/
Also, some operations use faster algorithms. Node failure detection is an important feature: EE has a distributed consensus algorithm that discovers when nodes go down, cancels queries, and can take advantage of replication to stay online during failure. With CE sometimes it is hard to distinguish between a failed node and a long running query.
That page is a bit outdated. I'll add a few items:
- 15.12 EE now has elasticiy: add more nodes to the cluster dynamically
- 15.12 EE also has namespaces, user authentication, security and permissions
In 16.9, which will be released soon there will also be more features, such as detailed query performance reporting.