I have added some definitions for you as there is often some confusion on the terminology and sometimes there is some overlap.
I hope this post is helpful:
Panic Attacks are very sudden, discrete periods of intense anxiety, mounting physiological arousal, fear, stomach problems and discomfort. The onset of these episodes is typically abrupt, and may have no obvious triggers.
Although these episodes may appear random, they are a subset of an evolutionary response commonly referred to as fight or flight that occur out of context. This response floods the body with hormones, particularly epinephrine (adrenaline), that aid it in defending against harm. Experiencing a panic attack is said to be one of the most intensely frightening, upsetting and uncomfortable experiences of a person’s life.
According to the American Psychological Association the symptoms of a panic attack commonly last approximately thirty minutes. However, panic attacks can be as short as 15 seconds, while sometimes panic attacks may form a cyclic series of episodes, lasting for an extended period, sometimes hours.
Panic attacks are commonly linked to agoraphobia and the fear of not being able to escape a bad situation. Many who experience panic attacks feel trapped and unable to free themselves.
The effects of a panic attack may vary from person to person. Some, notably first-time sufferers, may call for emergency services. Many who experience a panic attack, mostly for the first time, fear they are having a heart attack or a nervous breakdown.
Anxiety Disorders are often debilitating chronic conditions, which can be present from an early age or begin suddenly after a triggering event.
They are prone to flare up at times of high stress and are frequently accompanied by physiological symptoms such as headaches, sweating, muscle spasms, palpitations, and hypertension, which in some cases lead to fatigue or even exhaustion. Recent surveys have found that as many as 18% of Americans may be affected by one or more of them
Although in casual discourse the words anxiety and fear are often used interchangeably, in clinical usage, they have distinct meanings; anxiety is defined as an unpleasant emotional state for which the cause is either not readily identified or perceived to be uncontrollable or unavoidable, whereas fear is an emotional and physiological response to a recognized external threat.
The term anxiety disorder, however, includes fears as well as anxieties. Indeed, phobias (fears which are “persistent or irrational”) constitute the majority of anxiety disorder cases.
Agoraphobia is a common condition where the sufferer becomes anxious in environments that are unfamiliar or where he or she perceives that they have little control. Triggers for this anxiety may include wide open spaces, crowds, or traveling (even short distances).
This anxiety is often compounded by a fear of social embarrassment, as the agoraphobic fears the onset of a panic attack and appearing distraught in public. Thus they become confined to their house.
Phobia or morbid fear is an irrational, intense, persistent fear of certain situations, activities, things, or people. The main symptom of this disorder is the excessive, unreasonable desire to avoid the feared subject. When the fear is beyond one’s control, or if the fear is interfering with daily life, then a diagnosis under one of the anxiety disorders can be made.
Phobias are the most common form of anxiety disorders. An American study by the National Institute of Mental Health (NIMH) found that between 8.7% and 18.1% of Americans suffer from phobias.
Obsessive-Compulsive Disorder (OCD) is an anxiety disorder characterized by involuntary intrusive thoughts. When a sufferer begins to acknowledge these intrusive thoughts, the sufferer then develops anxiety based on the dread that something bad will happen. The sufferer feels compelled to voluntarily perform irrational, time-consuming physical behaviors to diminish the anxiety.
Sufferers often try to keep their compulsive behaviors hidden from others, often to avoid embarrassment, humiliation or to avoid being seen as strikingly odd or different from others. An OCD sufferer is able to recognize their thoughts and subsequent actions as irrational; which is what makes the illness so distressing, as the psychological self-awareness of the irrationality of the disorder may be extremely painful.
OCD is the fourth most common mental disorder.
Post Traumatic Stress Disorder (PTSD) is an anxiety disorder that can develop after exposure to one or more traumatic events that threatened or caused great physical harm. PTSD affects over 7.8 million people.
It is a severe and ongoing emotional reaction to an extreme psychological trauma. This stressor may involve someone’s actual death, a threat to the patient’s or someone else’s life, serious physical injury, an unwanted sexual act, or a threat to physical or psychological integrity, overwhelming psychological defenses.
In some cases it can also be from profound psychological and emotional trauma, apart from any actual physical harm.
