title: Difference between osv.osv class and models.Model class odoo 8
body: <p>Please let me know difference between osv.osv class and models.Model  class in odoo 8
  Example:</p>
  
  <pre><code>class account_invoice_line(models.Model):
  
  
  class account_invoice_line(osv.osv):
  </code></pre>