I am applying to pt schools for the first time this summer, and I have asked myself similar questions in regards to the schools I'm looking at. But I'm not trying to find one that is "easier" to get into, rather, I am looking at schools that require classes I have already fulfilled. Some schools require two semesters in biology, a requirement that I regret to say have yet to fulfill [I'm taking my 2nd bio class this spring, when it's too late to count 🙁] But I'm still applying to those schools because there's no harm in trying [except the cost to apply 😛].
I guess you could define "hard" by competitiveness, but who is to say that one is more competitive than another? they are all difficult to get into in their own way, that's why we all stress about getting into any school in this forum.
But to answer your question to the best of my ability, maybe look at the comparison of schools on ptcas [I believe there is a table with schools, requirements, etc] so you can decide what schools you may have the best chance of getting into. If USA has pre-reqs that you did well on, as opposed to other school's pre-reqs, then I guess it's "easier" to get into because you meet all the requirements. Said in a more logical way, you probably have a better chance of getting in, because you've done all the requirements well.
I hope this helps 🙂