Hi E.,
The only time I have heard induction referred to as "trial" induction is when the doctor feels a c-section may be necessary, but will "try" to get a vaginal delivery going via induction, but if it doesn't work, they will go for a c-section.
I was induced with Pitocin with my first delivery. My water broke two weeks early, and my doc gave me 18 hours to go into labor on my own. When that didn't happen , I was induced to avoid the risk of infection. With my second delivery, I went into labor on my own. There was very little difference. When I was induced, my pitocin levels were started off low and then gradually increased. contractions started normally and gradually got stronger. Really, the only difference was that I had to be on the monitors during my entire labor, so I couldn't roam the hospital, and had to unplug the monitors every time I went to the bathroom. My first labor (induced) lasted eight hours. They started the pitocin at 6 p.m., I was in active labor by midnight, and my son was born at 2 a.m. My natural labor was almost identical. I started having contractions at 10 p.m., arrived at the hospital at midnight, and my son was born at 5 a.m. (7 hours).
Contractions are painful, so to say that they are "worse" with an induction really doesn't mean much. Either way, it hurts.
Keep in mind that labor and delivery is not the same for all women, induction or not. Your sister's situation may be very different, if the doc is already thinking she may need a c-section anyway. But IMHO, it can't hurt to "try." If her only options are c-section or induction, I would definitely choose induction.