(PLR) Private Label Rights
Private Label Rights is a product that offers one of the best licenses around. PLR gives the user the rights to do just about anything they are wanting to do with it. For example, you can edit it, change the content, label it as your own (meaning claim authorship of it), sell for what ever price you are wanting. This license usually means you can do just about anything you are wanting to do with it.
(PU) Personal Use
Personal Use licenses can only be used for personal affairs, such as reading, sharing (only if stated), teaching. Products with PU cannot in anyway be resold or changed as this license restricts such acts. With personal use licenses you may make a unlimited amounts of backup copies. In most cases unless stated within the license itself or within the product, it cannot be distributed.
(CU) Commercial Use
This license allows you to distribute the product for your client's projects where you charge a price for your time and work. You can use a product with this license by you or any number of clients which the end-users (client) can be charged for.
(GAR) Give Away Rights
Give Away Rights is basically all digital products that have the rights to share, distribute across the internet give away to your subscribers on mailing list and basically anyone whois wanting a free product, you may give away freely. These products might even come with sale rights but it is not necessary to sell these products if you are just wanting to give them away for free.