how , according to Derry , was Mr.Lamb's disability different from his ?

give answer in 2-3 marks in easy simple language

Hi :)

Lamb was lame i.e. had a physical disability that people didn't shy away from or were repulsed by.
Derry had a disfigured face and claimed that people wouldn't even spare him a glance. So, he assumed he Lamb was better off.