Hi argyll1st,
If you look at the bottom of the Heartland website and click on Travel Trailers, you'll see the Prowler is grouped with several other models. It appears to be positioned above the lightweight travel trailers and below the mid-profiles.
I suspect you're wondering why there are so many similar choices. Sometimes there are similar models at similar price points to facilitate better market coverage while giving dealers an exclusive territory for the model they sell.
If the Standard Features and Options for each model doesn't help you answer your questions, you might call Heartland Customer Service at 877-262-8032 / 574-262-8030. Identify yourself as a prospective customer and ask for Ryan Brady, the General Manager of the Prowler/Trail Runner/Pioneer models. He or someone on his staff can give you more details.