Hi Thulasi,

You can find the difference usng monthsBetween() function in the apex class as below:

Lightning component:

<div class="slds-form-element__control date1 endate" for="date">
                            <ui:inputDate aura:id="frmdate" class="slds-input" value="{!v.fromdate}" displayDatePicker="true" updateOn="keyUp" /> 
                        </div>
                    
                        <div class="slds-form-element__control date2 endate " for="date">
                            <ui:inputDate aura:id="expdate" class="slds-input " value="{!v.enterdate}" displayDatePicker="true" updateOn="keyUp" /> 
                        </div>

Lightning Controller:

var fromdate=component.get("v.fromdate");
var toDate=component.get("v.enterdate");

var action=component.get("c.Difference");
action.setParams({

'fromdate':fromdate,
'toDate':toDate

});        
action.setCallback(this, function(response) {
var state = response.getState();
if (state === "SUCCESS") {
var storeResponse = response.getReturnValue();


component.set("v.diff",storeResponse);
} 
});
$A.enqueueAction(action);

Apex class:
 

@auraEnabled
public static Integer Difference(string fromdate ,string toDate)
{
Date dtfrom = date.valueOf(fromdate);
            date enterdatedt = date.valueOf(toDate); 
			Integer diff=dtfrom.monthsBetween(enterdatedt);
			return diff;
}

Thanks.​​​​​​​