ADO stands for ActiveX Data Objects and is a data access methodology that allows you to manipulate data in underlying data sources for VBA code. You use ADO to insert, update, delete, and retrieve data in databases that you want to interact with in your Access applications.
A disconnected (unbound) recordset does not maintain a connection to the database like a connected (bound) recordset does. Disconnected recordsets are typically better for reducing the number of open connections and record locks in your application. Disconnected recordsets are typically better because the data is cached locally until an update is made to the database. Disconnected recordsets require a little extra effort because you have to write code to handle navigation and updates to the data. Connected recordsets maintain a constant connection to the database, and Access has a lot of navigation features built-in for working with connected recordsets.
SQL stands for Structured Query Language and is a language that you can use to retrieve, add, update, and delete data in databases. SQL can be used in conjunction with ADO, or separately from ADO as part of your Access solutions.
The ADOX object model provides a library of features that you can use to manipulate databases, tables, users, groups, and security from your VBA code. The Catalog object is at the highest level of the object model.