A genetic disease is a disorder in the result of changes in a person's DNA. A lifestyle choice based disease is where your life style choices cause you to get the disease. An environmental diseases are diseases that are cause by environmental factors.
A change in a person's DNA is what causes it. They are affected by the disease because they have to deal with the disease due to abnormalities in the genes. Yes, there are many that can be treated, by surgery, medicine, etc. Autism is an example of a genetic disease. There are treatments to autism, but there are no known cures to autism. Autism is where there are struggles with communicating and relationships with other people.
Skin cancer is an example. Factors of the environment that are dangerous or you need less of can be huge causes skin cancer. They are affected by the disease because they may die from it or need to stay shaded from it which makes them not able to be outside. On the bright side, it can be treated with simple medications and careful circumstances. Skin cancer is an environmental disease. It is caused when people get too much sun and their skin becomes sensitive to it.
Diabetes is an example of life style choices. Life style and your choices greatly affects your risk of having it. They are impacted by life style choices because they have to cut back and sometimes have to avoid no matter what. People with diabetes may have genetics with it but it may also be life style choices.