mamtaR roy,
Welcome to JavaRanch.
Please take time to choose the subject line. It makes good sense if it something relevant e.g. for this post "Comparable vs Comparator" or "What is the difference between comparable and comparator" makes more sense.
Hope you have a wonderful time here.Wish you good luck.
In short we may say, comparator is used to compare two different objects. and comparable allows itself to compare with another similar object.
A ver good explanation can be seen on
this blog.
Hope that helps.

[ March 13, 2008: Message edited by: Anubhav Anand ]