Seizures -- abnormal movement or behavior due to unusual electrical activity in the brain -- are a symptom of epilepsy. But not all people who appear to have seizures have epilepsy. In contrast, epilepsy is a group of related disorders characterized by a tendency for recurrent seizures.
Non-epileptic seizures(called pseudoseizures) are not accompanied by abnormal electrical activity in the brain and may be caused by psychological issues or stress. This type of seizure may be treated with psychiatric intervention.
Provoked seizures are single seizures that may occur as the result of trauma, low blood sugar (hypoglycemia), low blood sodium, high fever, or alcohol or drug abuse. Fever-related (or febrile) seizures may occur during infancy and children usually outgrow them by age 6. After a careful evaluation to estimate the risk of recurrence, patients who suffer a single seizure may not need treatment.
Seizure disorder is a general term used to describe any condition in which seizures may be a symptom. In fact, seizure disorder is so general that it is not a useful term. Unfortunately, "seizure disorder" is often used to avoid the term epilepsy.