I haven't used it but just from looking at the Github page. It looks like redash has more advanced dashboarding features today (I'd like to catch up here). In contrast redash doesn't really allow you to manipulate data very much if it doesn't come in a form you want or if you can't get it into the right form with SQL alone.

DataStation allows you to script results of database queries (or loaded Parquet, Excel, CSV, etc. files or HTTP API responses) in Python, Node, R, Julia, etc.

Also, DataStation is first-off a desktop app today so it's very easy to install and use -- especially in a corporate environment. Data never leaves your laptop. In the future I think more people will use the server version of DataStation so you can get server features like recurring exports and hosted dashboards but desktop will always be supported too.