Conditional field in node type depending on user profile
If you want to hide a field from particular role via a contrib module, you can try

http://drupal.org/project/field_permissions

or if you're comfortable in code, see

hook_field_access

e.g:

function mymodule_field_access($op, $field, $entity_type, $entity, $account) {
  if ($field['field_name'] == 'field_of_interest' &amp;&amp; $op == 'edit') {
    // TODO: some special access check for TRUE or FALSE in $access
    return $access;
  }
  return FALSE; // default deny
}