How do you define the difference between ocd and worry?

Very different: Good question! "ocd" has almost become a household expression for simply worrying or caring a lot about something. But, statistically, obsessive -compulsive disorder occurs in only about 1-2% of the population. The disorder has two major components: intrusive and inappropriate thoughts (not worries about real-life problems), and repetitive behaviors aimed at preventing or reducing distress.

Somewhat alike: Worry and OCD are both qualitatively and quantitatively different. Ocd is more unwanted, repetitive, and about types of harm that are very specific. Worry tends to be more general, rational and not followed by rituals. Of course there can also be overlap.

DIFFERENT: Obsessive compulsive disorder does involve worrying but the hall mark is there are obsessive thoughts that lead to extreme anxiety with the resultant need to perform some compulsive or repetitive actions. Anyone can worry but fortunately not everyone has ocd.