The disease is something that can cause illness. This is usually caused by different factors. Some people may become exposed to disease and get it when the disease is contagious, while there are also some who acquire the disease by other means such as their lifestyle. There are some people who have a disease, but they are not even aware of it, but those who are feeling ill already know that they have a disease.
Illness can affect the process of the disease and make a person feel sick. Some people feel that being ill is not as serious as being sick, but some people feel that these things are all the same. Just remember that the disease is usually the cause, and the illness may be the result of the disease.