The main differences are as follows:

• Native: This allows the reviewer to view the document in its original form. This can be both an advantage and disadvantage. Native files need to be opened and viewed through applications that can understand their format. This can allow for variations from reviewer to reviewer, which can cause confusion.
• Tiff/Image: Tiffing is the process of printing a document and creating an image of the result. This allows the document to become “frozen” and thus standardizing what the reviewing parties see.