Here's your answer from the official Coast Guard website. All Type III's are required to have the same amount of buoyancy which is a minimum of 15.5 lbs
TYPE III PFDS / FLOTATION AIDS: For general boating or the specialized activity that is marked on the device
such as water skiing, hunting, fishing, canoeing, kayaking and others. Good for calm, inland waters, or where there is a good chance for fast rescue. Designed so that wearing it will complement your boating activities:
Inherently Buoyant Type III PFDs
Inflatable Type III PFDs
Hybrid Type III PFDs
...Note: The Coast Guard is working with the PFD community to revise the classification and labeling of PFDs. When completed, this information will be updated and hopefully be somewhat easier to understand. Meanwhile, spending a few minutes to understand the many options available to find a PFD that you’re willing to wear could mean the difference between life and death for you or a loved one.