I was using compare for password,confirm_password etc.It was checked by default operator of compare validation "==".
When I tried for >,I got a solution,there is a attribute of operator in compareValidaor.By which I achieve my goal.See rule,
array('end_date','compare','compareAttribute'=>'start_date','operator'=>'>','message'=>'Start Date must be less than End Date'),
similarly you can check <,<=,>=,> operators with it.
If you want to compare with value,
suppose percentage should be less than 100,you can do it with,'compareValue'
array('percentage','compare','compareValue'=>'100','operator'=>'<','message'=>'Percentage must be less than 100'),
Hope,It may helpful to others.