In the original 1958 TM, a single syllable (mantra) was used, and there were not "personal" mantras, that were introduced in 1969.
The results seem to be the same in both cases (read testimonials on the NSR website), but TM teachers (those who have not abandoned the TM organization) will tell you that personal mantras are necessary to make TM unique, so that TM results can't be achieved in any other way. You compare, you decide. Here is what TM teachers will tell you:
1) different, personal mantras are indispensable for an effective meditation;
2) no technique is as effective as TM;
3) no valid technique can be learned through a manual;
4) you must spend $2500.00 if you want to learn an effective meditation (TM).
In other words, they acknowledge that the NSR technique is not TM, and NSR is not concerned with trademark or copyright problems. Some scientific research on NSR (that is very small if compared to that on TM) has shown that the remarkable effects of NSR seem to be the same as TM.
Why is Transcendental Meditation so expensive? (US$2500.00)
We don't know. Probably the TM organization considers TM very beneficial and precious (and it is), but they forget that most people cannot afford such expense. Many TM teachers are disappointed for this absurd price, that is imposed by the International TM Organization. See for example TM Independent UK. Many TM teachers are also disappointed for the expensive course of "recertification" they must attend ($16,000 + room and board)! This was a new, unexpected, absurd decision of the TM organization (Spring 2005). However, Maharishi himself said: "30 or 40 thousand teachers of TM I have trained, and many of them have gone on their own, and they may not call it Maharishi's Transcendental Meditation, but they are teaching it in some different name here and there... doesn't matter, as long as the man is getting something useful to make his life better, we are satisfied" (Maharishi Mahesh Yogi, Press Conference, May 14, 2003).