John
A photo of the drawing might help because there can variations in terminology:
The hog is the internal part of the heel.
The horn is where the hog goes upwards and may take the sternpost for the rudder or a transom. Traditional the hog would be one piece of wood in a small vessel and scarf joined in a larger one. The horn is often built up from a number of different pieces of wood either spiked or bolted together. Yours is combined as that is much simpler in a model.
The inwhale normally means a timber that runs around the edge of the top of the hull either inside or notched into the ribs or frames. Sometimes it can be a number of pieces fitted in between the ribs or frames. I have not heard of an inwhale frame.
If it is a kit they don't always get the names quite correct.
Tim R