What do you mean, sick?

Sick and sick have "sick; Sick ",but the usage is not exactly the same.

Ill means "sick; The meaning of "sick" is generally used as a predicative, not an attribute; Sick can be used as both predicative and attributive. For example, a "patient" can be said to be a sick person or patient, but not a sick person or patient. She is ill in bed. She is ill in bed. She is taking care of her sick father. She is taking care of her sick father.

Sick is "disgusting; The meaning of "tired". The smell makes me sick. The smell makes me sick.

Ill is "bad" when it is used as an attribute to modify nouns; Evil means evil. He is a bad man. He is an evil man.