Create member login using Rails 3

I have a doubt regarding member login using Rails 3.Let me to explain below my plan about creating member by Admin .

I have already done the admin login(views/admins/index.html.erb).Only Admin user can create member after login inside home page.As my login page and login method will remain same. Member also can login from that same page.But i want to create new model for the member(lets say 'User') so how can i differentiate both model in the same method(i.e-login).I am explaining my code below.

views/admins/index.html.erb

<div id="login">
  <div id="triangle"></div>
  <h1>Log in</h1>
  <%= form_for :admin,:url => {:action => "login" ,:controller => "sessions" } do |f| %>
  <%= f.email_field :email,placeholder:"Enter your email" %>
  <%= f.password_field :password,placeholder:"Enter your password" %>
  <%= f.submit "Log in" %>
  <% end %>
  <% if @admin.try(:errors).try(:any?) %>
                                      <div id="error_explanation">
                                      <h2><%= pluralize(@admin.errors.count, "error") %> prohibited this post from being saved:</h2>

                                      <ul>
                                      <% @admin.errors.full_messages.each do |msg| %>
                                     <li><%= msg %></li>
                                     <% end %>
                                     </ul>
                                    </div>
                                  <% end %>
</div>

sessions/sessions_controller.rb

class SessionsController < ApplicationController
    def login
        @admin=Admin.authenticate(params[:admin][:email], params[:admin][:password])
        if @admin
            session[:user_id]=@admin.id
            cookies.signed[:user_id]=@admin.id
            flash[:notice]="Login Successfull"
            flash[:color]="valid"
            redirect_to :action => 'index', :controller => "homes"
        else
            flash[:notice]="Login failed"
            flash[:color]="invalid"
            render 'admins/index'
        end
    end
    def removeadmin
        session[:user_id] = nil
        cookies.delete :user_id
        flash[:notice]="user logged out successfully"
        flash[:color]="valid"
        redirect_to :action => 'index', :controller => 'admins'
    end
end

model/admin.rb

class Admin < ActiveRecord::Base
  attr_accessible :email, :name, :password, :phoneno
  EMAIL_REGEX = /\A[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\z/i
 validates :email, :presence => true, :uniqueness => true, :format => EMAIL_REGEX
 validates_length_of :password, :in => 6..20, :on => :create
 def self.authenticate(email, password)
    admin = find_by_email(email)
    if admin && admin.password==password
      admin
    else
      nil
    end
  end
end

homes/index.html.erb

<% if current_admin %>
<div class="header">
<div class="navbar-header">Swargadwar, Puri Municipality,govt of odisha</div>
<div class="nav navbar-top-links navbar-right">
<div class="image"></div>
</div>
<div class="name-div">
    Logged in as:<%= current_admin.email %>
</div>
</div>
<div class="menu-div">
<div id="leftsidebtn">
 <ul>
   <li><a href="#">Create User</a></li>
   <li><a href="#">Scan Report</a></li>
   <li><a href="#">View and Payment Report</a></li>
   <li><a href="#">Payment Validate</a></li>
   <li><a href="/sessions/removeadmin">Log Out</a></li>
 </ul>  
</div>
</div>
<div class="content-div">
</div>
<% end %>

I want to create another model for member(i.e-User) and do the authentication inside user.rb for user/member loin but my login method is same.Please help me how can I differentiate Admin and User model after putting email and password on same login page from login method. Please help me.