Object.operator !=  

var target : Transform;
function Update () {
// the target object does not refer to the same object as our transform
if (target != transform) {
print("Another object");
}
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
public Transform target;
void Update() {
if (target != transform)
print("Another object");

}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

public target as Transform

def Update():
if target != transform:
print('Another object')