This article is from the Epilepsy FAQ, by Andrew Patrick (firstname.lastname@example.org) with numerous contributions by others.
Epileptic seizures and pseudoseizures are distinguishable both by their
nature and symptoms, but the diagnosis can be difficult. Epileptic
seizures are caused by a change in how the brain cells send electrical
signals to each other, while pseudoseizures are triggered by a
conscious or unconscious desire for more care and attention. Thus,
measuring brain activity with an EEG and video telmetry is important
for distinguishing epileptic and pseudoseizures. Also, pseudoseizures
often lack the exhaustion, confusion, and nausea that is associated
with epileptic seizures. Psychogenic seizures can occur in people who
also experience epileptic seizures.