This is explainable from a boy who does this…

Common cold - I want to be allowed to rest and be taken care for(for example “I’m sick so can you cook me some soup and a sandwich for lunch?”).

Life threatening illness - I don’t want to make the person worry about me. I don’t want them to force me to a hospital which I cant afford.

You’re not going to worry or take me to the er for a cough but you would probably care for me and pamper me… That’s the difference