Since there is no Drupal 7 version for Views Mail, there is nothing to compare. Also note that the Drupal 7 version of Views Send doesn't use VBO anymore.
Views Send is a better choice than Views Mail because it:
- Passes everything through Views Bulk Operations (VBO). That's why the UI is very intuitive for users. The flow is more accurate and clear.
- Doesn't need tagged Views.
- Doesn't rely on Simplenews.
- Avoids some limitations of Views Mail, like:
- Avoid using AJAX.
- Avoid defining arguments.
- Avoid limiting records per page - you can use the pager system.
- Benefits of performance improvement through Views Bulk Operations (VBO) by using the batch processes implemented by VBO.
- Has a more clear API - mostly hook implementations.
- Allows the user to manually select records (in addition to View filtering) by using Views Bulk Operations (VBO) checkboxes.