Unity3d control object movement

there are two way to control object movement:

1. By directly manipulating the transform of a object

   using UnityEngine;
   using System.Collections;

public class movementControl : MonoBehaviour {

public float moveSpeed = 10f;

// Use this for initialization
void Start () {

}

// Update is called once per frame
void Update () {
    if(Input.GetKey(KeyCode.UpArrow))
        transform.Translate(Vector3.forward * moveSpeed * Time.deltaTime);

    if(Input.GetKey(KeyCode.DownArrow))
        transform.Translate(Vector3.back * moveSpeed * Time.deltaTime);

    if(Input.GetKey(KeyCode.LeftArrow))
        transform.Translate(Vector3.left * moveSpeed * Time.deltaTime);

    if(Input.GetKey(KeyCode.RightArrow))
        transform.Translate(Vector3.right * moveSpeed * Time.deltaTime);
}

}

2. By using physics Rigidbody add force

   using UnityEngine;
   using System.Collections;

public class moveControl : MonoBehaviour {
private Rigidbody rb;
// Use this for initialization
void Start () {
rb = GetComponent<Rigidbody>();
}

// Update is called once per frame
void Update () {
    float x = Input.GetAxis("Horizontal");
    float y = Input.GetAxis ("Vertical");
    rb.AddForce (x, 0, y);
}

}