A cyst is a closed sac-like structure that can be filled with fluid, gas, or other material. It is usually found under the skin and may be caused by a variety of factors, including infection, inflammation, or trauma. A cyst is usually not serious and can be treated with antibiotics or other medications.
An abscess is a localized collection of pus that is caused by infection. It can be found anywhere on the body and is often accompanied by pain, swelling, tenderness, and redness. An abscess requires medical treatment to be properly treated, usually with antibiotics and drainage of the pus.