Guinea hog weight confusion

We are prepping to kill some pigs. I went out to get measurements to do the weight estimates on a variety of the pigs and the results are confusing.

Our boar is roughly 452lbs live weight. The sow we originally bought to breed with him is roughly 324lbs live weight. This is what we expected them to weigh.

A year after buying our first pigs and after having failed to breed the sow I bought 2 more gilts. These ones were much smaller when we got them and haven't grown overly much. They are roughly 152lbs live weight. When I bought them she said I could register them if I wanted but I chose not to.

The 2 small sows have had babies and while I couldn't measure the smallest ones (still skittish and unwilling to let me close) I was able to get some of the older piglets measured. They were born July 23. They weigh roughly 56lbs live weight.

I guess I'm confused. What did I buy here? They can't possibly all be guinea hogs. The size difference is too huge. Or can they be? I just don't know.

Hi Elle:   From what I gathered at wikopedia , there are 2 types of Guinea hogs, large boned and small boned. Longer legs and I would assume higher weight.  
They don't differentiate between the two, just say that males and females are under #300.