Intense means something at an extreme degree or strength. It is often used for describing activities or human feelings beyond a certain degree.
The task required intense concentration.
The project generated intense interest from the investors.
There is intense competition between the two companies.
Intensive refers to a process which involves continuing efforts.
We are offering intensive courses for developing communication skills.
The inventory was sold by means of an intensive sales campaign.
Intense means strained; tightly drawn. It details a quality or condition (The cold was intense). Intense means of severe strength or force; having strong feelings. Emotions can be intense. An intense course is an extremely tough course, such as advanced nuclear science.
Intensive means focused on one subject or area for a short time; extremely thorough. So for example, an intensive course would be very focused on one topic and would last short time, as with summer courses. An action that is sustained (such as attention or an application) is intensive. Intensive comes from the outside, it is imposed or assumed. Intensive implies that the degree or force is very high or strenuous (e.g. He received intensive training).
