Notice how all the pieces fit together. But there are many variations. As for bodies, they can be two piece, three piece, or four pieces. Legs and arms can be one or two pieces. If you have a two piece arm, the paw pad can either be separate or part of the two pieces.
Footpads are almost always separate, especially on big bears.
But the ear can be put in the gusset seams or sewn on after the head is completed. Naturally, the first pattern you design will be the most difficult. After that, you can always design the second by making changes to the first. But I took that pattern, made a number of changes, and created a pattern from it that I still use today and have received compliments on. If you're fortunate, your first bear will be great the way he is, but chances are you'll have to make a few changes.