1)IS there any possibility for Altcoins to be hacked ?
2) Difference Between Bitcoin and altcoin in security ? if they are same why Bitcoin price far away from other altcoin if they same ?
If you do not secure your wallet properly, your bitcoin wallet can be hacked and you will lose your coins. The same applies to altcoins, you must secure them properly otherwise you are at risk of losing them. I have no idea what alt coin concerns you, If possible use an offline wallet.