CONNECTED Architecture:

• In connected architecture, the CONNECTION must be kept open for accessing the data retrieved from the database. Connected architecture is based on Connection, DataReader, Command, and Transaction classes.
• You constantly visit the database for any CRUD (Create, Read, Update, and Delete) OPERATION you want to do. This will create high traffic to the database, but this is usually faster as you are doing only smaller transactions.
• DataReader can be SAID as a Connected Architecture as it holds the connection open until it fetches all the rows one by one.

Disconnected Architecture:

• In disconnected architecture, even if the database connection is closed, data retrieved from the database can be accessed. Disconnected architecture is based on classes connection, CommandBuilder, DataAdapter, DataSet, and DataView.
• Here, we RETRIEVE and store a recordset from the database so that you can perform many CRUD (Create, Read, Update, and Delete) operations on the data within memory, it will be re-synchronized when you reconnect with the database.
• DataSet is a Disconnected Architecture because all records are brought at once and holding the database connection alive is not necessary.