How to give users with role Role2 the right to edit only user accounts with role Role1
You may want to try Administer Users by Role module.


  This module allows site builders to set up fine-grained permissions
  for allowing "sub-admin" users to edit and delete other users — more
  specific than Drupal Core's all-or-nothing 'administer users'
  permission. It also provides and enforces a 'create users' permission.


One of the extra permissions that this module provides is

Edit users with custom roles - Allows editing of any authenticated user with the specified role.