The Chicago school year is 174 days with 5.75 hours per day, for a (rounded) total of 1001 instructional hours per year. The New York City school year is 186 days with 6.83 hours per day, for a (rounded) total of 1271 instructional hours per year.
The cumulative difference is striking, and is graphically depicted below (click to enlarge). By the time a New York City student has graduated, while being in school for 12 years, they have effectively been educated for 16.51 Chicago school-years. Prima facie, a remarkable disparity.