Is there a difference in symptoms between fainting due to heart and fainting due to neurological reasons?

Difficult: To sort out at times since the symptoms often overlap. A good history and physical is critical. See your doctor for evaluation.

Oh yes!: Syncope (fainting) from cardiac reasons is most often due to changes in rhythm (though there are less common cardiac causes) and is often fairly sudden; you might have no warning, or only a few seconds. Fainting from neurologic causes can be sudden, yes, but sometimes has a much more prolonged "build up" of symptoms. These can include: headache, hot/cold, whooshing in ears, dizziness, and more.