DSpace 7 improves upon the previous version in a number of ways:

• A better overall architecture with a clear separation between business logic & presentation thanks to the development of a new full fledged HATEOAS REST API
• A sleeker more modern user interface.
• The Angular codebase for the user interface facilitates customization and further development.
• Improved statistics.
• The Collection structure has been simplified ...?

Other DSpace 7 important resources:

• A recent summary of the project status from Tim Donohue: http://duraspace.org/articles/3157
• The DSpace 7 Working Group page