The PT takes at least one more year of education - MPT level qualification is being phased out in favor of DPT level of qualification, which is a 3-year program beyond undergrad. You can practice as a PA with just a master's, and there are some baccalaureate PA programs that take just over two years to complete and that you can do generally once you have completed 2-3 years of undergrad. So that's 7 years for the PT program vs. anywhere from 5-6 of the PA program.
However, the caveat is that most PA programs require you to have hours of experience as a clinician (such as a nurse, a certified nursing assistant, EMT, paramedic, etc.) The hourly requirements are quite extensive (around 1,000-2,000 hours for the best programs), and those are minimums. At 40 hours a week, it takes 50 weeks (or about a year) to obtain 2,000 hours of experience. Most people in PA programs are nurses, EMTs, paramedics and other health care personnel with 3-5+ years of experience looking to move up/make a better salary/have more responsibility and direct care for patients.
PT programs don't have the same requirements, although many of them do require a certain number of hours shadowing or working with a physical therapist. But it's work that you can do as a student.
PAs make a little bit more than PTs. The median annual salary for PTs was $72,790 in May 2008, whereas it was $81,230 for PAs. The middle 50% of PTs made approximately $60-85K, whereas the middle 50% of PAs made approximately $68-97K per year. (Bureau of Labor Statistics: Physician Assistants
, Physical Therapists
The rest is subjective and depends on where you work and who you work with. Both physical therapists and physician assistants can work in hospitals, clinics, private physicians' offices, nursing homes, rehabilitation centers and a range of other health care institutions. The work you'll do will vary based upon that.