Distinguish between obsessions and compulsions.
Obsessions refer to the inability to stop thinking about a particular idea or topic. The person involved often finds these thoughts to be unpleasant and shameful. It is essentially a preoccupation with specific ideas that the individual is unable to control.
On the other hand, compulsions refer to the need to perform certain behaviours over and over again. This repetitive behaviour affects the person's ability to carry out normal activities. Many compulsions deal with actions like counting, ordering, checking, touching, and washing.
Explanation
The answer distinguishes between the two concepts based on the textbook definitions. Obsessions are cognitive (inability to stop thinking about an idea, often unpleasant/shameful), whereas compulsions are behavioural (need to perform acts repeatedly, like washing or checking).