Cluster headaches are severe type of headaches which often occur in middle of the night and affect men a lot more commonly compared to females.
The pain in migraines can be as severe, but is often longer lasting. The head pain in cluster headaches is often accompanied by eye
redness, etc.The exact mechanism isnt known. You can good info on http://www.Nlm.Nih.Gov/medlineplus/ency/article/000786.H.