Tom Doak (in his architecture book) wrote up the three types of hazards generally used - penal, strategic and heroic. A course (and a golf hole) uses all 3 types, with different architects/courses empahasising one more than others. This was a fundamental learning for me when I became interested in GCA.
Penal and strategic are well described above. Heroic carry is a slant on strategic - you can play around the hazard, but if you can carry the hazard you get a significant reward. If you play wide of the hazard, you can but a more difficult shot awaits you.
A strategic hole might allow a player to go close to the hazard, and get home in one more shot whereas if he played wide of the hazard he might need a second shot followed by a pitch.
Tom Doak referred to MacKenzie/Jone's Augusta Amen Corner as a classic combination of the three styles.
The 11th is classic strategy - you can take on the water hazard by the green or play wide and chip on.
The 12th must carry Rae's Creek - you can't avoid it (penal).
The 13th combines all three types, but the heroic carry involves the tee shot (carry the creek at the corner) and the second shot (carry the fronting creek, especially from the lhs , ie more strategic position).
Penal and strategic do not imply the severity of a hazard, rather the design purpose. A strategic bunker can be very deep, whereas a shallow cross bunker (penal) may be quite easy to play out of. Contrast the penalty of a ball lost in Rae's Creek on #11 and #12 (lost, never to be seen again) and #13 (retrievable, possibly enticing you to play it from the creek.
Hope this helps. I recommend Tom Doak's book (Anatomy of a Golf Course) for the full explanation.