A Qari is someone who has learnt the rules of tajweed and correct pronunciation of the Quran ..i'm not sure what you mean by Sheikh-ul-Islam :-[
Generally a Sheikh is someone who has learnt the Quran/Hadiths to a high level but i'm not sure if they're is a difference in Sheikh and Sheikh-ul-Islam :-[
Hope it helps Inshallah
P.S Some people add Sheikh as a means of showing respect