I'm sure folks have said this 1000 times already, but I think the Strategic school of design emphasizes options to get a good score, while the Penal school of design has only one option for a good score, though there may be various lay-ups if you are willing to accept bogey or worse (ergo, RTJ's hard par, easy bogey). Just because a hole is difficult or a bad shot is penalized doesn't mean it is one school or the other. In fact, hazards must be difficult in a strategic design, otherwise, there's no reason to consider the less risky option.
The most basic example of strategic (a bit simplistic, clearly) is a central fairway bunker - you can go right, left, over or in front, leaving different types of approach shots, but it's your choice. Now, instead of the central bunker, think a big mess of trees or water along the line of the formerly central bunker on the left (or right), and another big line of trees or water on the fairway edge of the other side. Now you have only one way to play the hole to try to get a decent score - down the center. You can hit less club to try to make sure you keep it in the center, but center is all there is.
Obviously, strategic designs are more interesting than the simple example (green tilting one way and the center bunker a little to the right or left, a la 14 at St. Andrews, making the tee shot option giving with the best approach more difficult), but I think options are at the heart of the strategic school, and specific shot requirements of the Penal school.