synchronus reset with simple respected clock.it is required more no of gates,and it is didnt have metastabilty problem.it is working is slow. u6 T# z3 r$ n' }4 T) G. P9 w 9 K, T! ]; F! k! q9 r! Nasynchronous reset with out respected to the clock.it is required less no .of gates.it is suffer to the metastability problem.it is working is fast