After a bit of discussion at an open skate about what's the difference between a hockey stop and a powerslide I had a bit of a careful look into some instruction vids on youtube
They're basically the same thing (i.e. the idea is to stop from high speed as quickly as possible) but Bonnie's power slide is:
Skating forward
Skating sideways (briefly)
Face backwards, push back foot out to brake
whereas the hockey stop is more throwing a turn into a plough stop
In one case an artistic skater on youtube does a hockey stop by just quickly turning both skates in one direction (keeping legs close together rather than going into plough stop)
Some screen grabs (link to vid below the screen grabs)
Powerslide:
Youtube: Boonie D. Stroir - How to do a power slide
Hockey stop (focusing on skater in green on right):
Youtube derbydiva.com how to do a hockey stop