Would it be safe to assume that TA and tutor are the same thing?
In my experience (at a US school), "tutor" usually refers to someone who gives one-on-one instruction.  Usually this is not part of the course itself, but is something that students who need help seek out independently (that is not to say that the school or department might not have some program for tutoring, but it's usually not considered "part of the course").

In contrast, a TA is someone who does grading, leads review sessions, helps proctor exams, or some other activity related directly to the course.  A TA often also has office hours for one-on-one help, but this is not their only duty.