Ganisher,
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<style type="text/css">
.errorstyle{
border: 1px solid #ff0000;
background: #fff3f3;
}
.erroric{
color: #ff0000;
font-weight: bold;
}
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<script type="text/javascript">
$(function(){
let popupin = {
title: '<p class="erroric text-center">ERROR!</p>',
content: '<p>The value of the first "input" must be less than the value of the second one!</p>',
html: true,
trigger: 'hover',
placement: 'bottom'
};
$("#less").popover(popupin).popover('disable');
$('.container').on('focusout', '#less, #more',function(){
let less = $("#less").val().trim();
let greater = $("#more").val().trim();
if(greater)
if (+less >= +greater) {
$("#less").popover('enable');
$("#less").addClass("errorstyle");
}else{
$("#less").popover('disable');
$("#less").removeClass("errorstyle");
}
});
});
</script>
</head>
<body>
<div class="container">
<div class="form-group">
<label for="camp">Less:</label>
<input type="number" class="form-control" id="less">
</div>
<div class="form-group">
<label for="comp">More:</label>
<input type="number" class="form-control" id="more">
</div>
</div>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
</body>
</html>