This is how the two are described/classified by Mark Twight. This information came from the schedule headings/descriptions off of The Gym Jones web site.
www.gymjones.com
Power:
"This is used to describe several types of workouts. Typically the movements used are fast and explosive (e.g. the Olympic lifts). These would be done at a load heavy enough that repetitions are restricted to less than 5 per set. Box Jumps, Depth Jumps and Litvinov Conversions fall under the Power heading. These workouts are aimed at increasing rate of force production, and the ability to "turn on" muscle fibers instantly in a coordinated manner. "Power" is also used to describe workouts where maximum cardiovascular stress is imposed for a short period, usually 30 to 90 seconds, with the common example being to Row 500m."
Power Endurance:
"Predominantly cardiovascular in nature, though the cause of stress on the O2 system may derive from any source (run, ride, lift, swing, jump, etc). Due to the duration and intensity energy is supplied by roughly equal levels of aerobic and anaerobic sources (3-8 minutes steady state). Or it may be an effort requiring intermittent, repetitive power production over long period (e.g. 10 minutes of KB Snatches). We also use the term to describe hard and fast endurance efforts lasting up to 20-30 minutes because we consider these to be short, not the realm of genuine endurance."