Difference between monostable multivibrator and astable multivibrator?

No, cant use bistable multivibrator in place of monostable multivibrator... because monostable is meant for one stable state and one unstable state.. so there will be a constant time period for the alternate pulses of output.. but in bistable multivibrator, both are stable states.. so there is no specific time period for the output pulses.. the state will vary only on the application of mannual trigger...