yes, in the pure definition of the word in the world of print, Crop DOES equal trim...in the exact concept of what YOU see it as.
in Adobe's little bubble, they decided to call the outer box the "Crop" so that they could differentiate between trim and crop in the page box model.
These pictures should help, if not, I'm not going to continue to explain something that you don't want to grasp.
Each picture shows what Acrobat is calling each page box line. since they felt the need to call one trim and one crop, you have to widen your concept of what Adobe is defining "crop" as. Not saying its right, but it is what they are doing, and what is causing the whole issue.
All that aside, if you are not understanding the page box model, then your PDFs are probably not set up this way, so you probably wouldn't even notice the change... So why are you posting on this thread?