ASP.NET

What is difference between Eval() and Bind() Method???

Hai All, 
I am having two methods in a single service below. I will host this service in IIS. I will be having only one service URL. Client will consume this service by creating the proxy class as usual. But Mehod1 should only be displayed to Client A,  Mehod2 should only be displayed to Client B. How can I overcome this scenario?.. Can you please clarify my doubt..? Thanks in Advance

namespace serviceHide
{
    [ServiceContract]
    interface IServiceHide
    {
        [OperationContract]
        string Method1(string id); //This method should be displayed to Client A only

        [OperationContract]
        string Method2(string id); //This method should be displayed to Client B only

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class plrsmkt_calculation : System.Web.UI.Page
{

    protected void Page_Load(object sender, EventArgs e)
    {
            }

    int totalrs = 0;
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            totalrs += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "rs"));
        }
        else if (e.Row.RowType == DataControlRowType.Footer)
        {
            e.Row.Cells[1].Text = "Total";
            e.Row.Cells[1].Font.Bold = true;

            e.Row.Cells[2].Text = totalrs.ToString();
            e.Row.Cells[2].Font.Bold = true;

            e.Row.Cells[3].Text = totalrs.ToString();
            e.Row.Cells[3].Font.Bold = true;

        }


    }
    protected void TextBox1_TextChanged(object sender, EventArgs e)
    {

    }
}