The biggest difference is that Motor Admin has a convenient self-hosted option with a single click deploy. Self-hosted comes with many benefits like custom domain, ability to host under VPN, and faster UI due to lower network roundtrip and CORS avoidance.

Also, Motor Admin open-source version has powerful business intelligence features with custom SQL reports, BI dashboards with variables and fields, and automated email reports.

Also Motor Admin's UI is optimized on mobile and the UI is faster in general.

In terms of available features open-source, self-hosted Motor Admin could become a much better option than ForestAdmin SaaS for an admin interface.