Difference in Extention and Intention?

What is the difference between Extention and Intention?

Extension is the number of tuples present in a table at any instance. This is time dependent. Whereas Intension is a constant value that gives the name, structure of table and the constraints laid on it. Please view this link for more details:
http://www.freetutes.com/systemanalysis/sa8-extensions-intensions-relational-database-model.html