system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 the difference between an illness and a disease.
gpt
An illness is when you feel bad.  You have pain, soreness, dizziness, you might feel tired, etc.  You are not sure why you fell bad, you just do.  Basically, illnesses are feelings, a list of complaints.

A disease is when there is something actually wrong with you physically or mentally, whether you feel it or not.  Things like cancer, diabetes, and depression are diseases.

In many cases, illness is caused by the disease.  For example, diabetes (disease) can make you feel weak and disorientated (illnesses).  Sometimes, a disease might not cause any illnesses.  A person with cancer may not feel a thing for a long time.  Also, sometimes illnesses occur without a disease.  You might have a headache, but there nothing serious that is causing it, just stress.