Spreadsheet.com is an independent company and product that shares similarities to a number of collaborative work tools.
Regarding Airtable specifically, the primary difference is that Spreadsheet.com is a fully functional traditional spreadsheet with the capabilities of an easy to use relational database, while Airtable is a relational database with some characteristics of a spreadsheet. More details here: Comparison between Spreadsheet & AirTable
The Spreadsheet.com Community board runs on Discourse, a popular community platform also used by Airtable.
Hope this helps. We’d be happy to connect directly to answer any specific questions about permissions, the differences between our product and others, etc. You can contact us via email at info@spreadsheet.com.