Depending on your workflow, you may or may not utilize the Approval feature when responding to reviews. If another user is going to Approve or Post your response, the initial step would be to Submit for Approval. From there, your response will be pending until it has been Submitted as Posted.
If your work flow does not require any other user to approve or post your response you can disregard this option.
For Facebook and Google profiles connected via OAuth, you are able to post directly to the review site from your dashboard by clicking the Submit and Post to Google (or Facebook) button.
For all other review sites, you will have to submit as posted and then choose the post icon to actually paste the response to the review site so it is public. For internal reviews, the Post button will actually direct you to email the customer directly since internal reviews are not hosted on a public review site.
A review response can be marked on hold if there may be more information to gather prior to responding.
There is also an option to leave internal notes when necessary. This is within your dashboard and can be for personal use or to communicate with other users in the dashboard.
For Internal reviews, a response would be sent to the email provided by the reviewer. Since internal reviews are not located on a review site, this is the only option.