According to scientific literature, Type A behavior is characterized by an intense and sustained drive to achieve goals and an eagerness to compete. Personalities categorized as Type A tend to have a persistent desire for external recognition and advancement. They are involved in various functions that bring about time restrictions. Such personalities have a tendency to speed up mental and physical tasks with extraordinary mental and physical alertness. These characteristics make for super-achievers and high-powered people.
Type A individuals can get a lot done and have the potential to really move ahead in the world. But there is a high price to pay. Certain components of such a personality can inhibit happiness and even threaten health. For example, the goals that Type A folks set are often poorly defined and therefore hard to achieve-a perfect recipe for misery.
Type A is also characterized by a general discontentedness and the impulse to be overly critical and demanding, even contemptuous of imperfection, in the self and others. This focus on negative aspects and the accompanying bursts of hostility and impatience result in guilt, remorse and anxiety.
Type A personalities are motivated by external sources (instead of by inner motivation), such as material reward and appreciation from others. Type A folks experience a constant sense of opposition, wariness, and apprehension–they are always ready for battle. And anyone can imagine how this constant (and very exhausting) existence would deplete reserves of contentment and happiness and disrupt personal equilibrium.
Although the literature is somewhat inconsistent because of problems with the conceptualization and definition of Type A behavior pattern, it has been linked to higher risks of cardiovascular diseases. The risks seemed to be reduced with intervention aimed at reducing Type A behavior. Indeed, those with a high Type A score would be happier and healthier if they were to file down the jagged edges of their personality. By learning how to control the negative behavior patterns while preserving their drive, Type A people can be successful without sacrificing their emotional well-being.
Type B behavior is usually defined as the absence of Type A behavior. Type B personalities are relaxed and have a laid-back attitude and posture. They are friendly, accepting, patient, at ease, and generally content. They are at peace with themselves and others. They show a general sense of harmony with people, events, and life circumstances. They tend to be trusting. They focus on the positive aspects of things, people and events. Type B folks are self-encouraging, have inner motivation, are stable and have a pleasant mood. They are interested in others and accept trivial mistakes. They have an accepting attitude about trivial mistakes and a problem-solving attitude about major mistakes. They are flexible and good team members. The Type B person is able to lead and be led.
source : http://health.discovery.com