The key difference between caricature and a portrait of someone is the intentional
distortion of the subject in caricature. This distortion is difficult because the features of the subject are what makes the subject recognizable, when you start fooling around with these features, then you run the risk of loosing the likeness of the subject.
The caricatures and cartoons are considered the same thing. The difference between the two is a caricature is simply a cartoon of someone or something that the viewer can recognize as a specific someone or something. As soon as someone known by the viewer is seen in a cartoon, it becomes a caricature.
Today, the art of caricature is still around, though nowhere near as prevalent as the "Golden Age" of the 20's and 30's. In recent years there has been a rise of amateur "On-the-spot Caricaturists" who can be found on street corners or fairs and will draw a quick sketch of anyone willing to pay their fee. The word "caricature" can also apply to a person or thing that displays behaviour or mannerisms that are ridiculously exaggerated and overly stereotypical.