what is yhe difference between capacitor & battery.i am unable to get any clear idea about the both.can u send me a detail information about this,plz

A capacitor cannot maintain a const p.d across a circuit. After the capacitor discharges completely, no current is obtained. A capacitor discharges in a very short interval of time. On the other hand, a battery can maintain a const p.d. for a long period of tim. A  battery also gets discharged, but discharging may takes years also.