I have no idea what the N and T words are supposed to be. (I hate it when someone says "the <enter random letter here> word" and expect me to understand - I feel stupid. xD)
Anyway, uhm... Well ->-bleeped-<- is a term very much disliked by transsexuals because of the uproar Ray Blanchard's research caused and the various bad implications it had (both in medical professionals, who mistakingly took autogynephilic MTFs as "not real transsexuals" rather than "a different kind of transsexual", and in trans people themselves, who saw it as misogynistic without looking at it in detail and denied its existence), but it's nevertheless coherent with what scientific findings suggest, for there being two kinds of transsexuals:
-"Homosexual transsexuals", transsexuals who, in regards to their birth sex, are exclusively or primarily attracted to the same sex (post transition those would be MTFs who are (or mostly are) into guys and FTMs who are (or mostly are) into girls). The need leading to transition, in those, tends to rely much on a reasoned decision about their cross-gendered personality and behaviour not allowing them to have a normal and fulfilling life as their birth gender.
Those tend to transition young or not transition at all because of their strong drive to have a normal life. If you've set your mind and found a place in life where you can be happy with being a very butch woman or a very feminine man, then you should be satisfied, and changing your mind at 40 years old is counter-productive, both because you'll pass as the target gender less easily and because you've had the time to establish yourself a life that would be hard to make "normal" if you threw everything into chaos by transitioning.
In that sense, many gay men and lesbian women could perhaps be described as having roughly the same problem as "homosexual transsexuals", in that their cross-gendered personalities/behaviours may make life more difficult for them, in a milder form. Oversimplifying this could result in "transsexuals of that type are so gay/butch that they're girls/guys", which isn't all that false.
-"Autogynephilic transsexuals" (in FTMs, there's "autoandrophilic", but it's still just a hypothesis due to how they rarely if ever showed up in research and lack of research altogether, and the differences that seem to appear between MTFs who are into girls and FTMs who are into guys suggest that there might be another mechanism involved). I'm going to refer to MTFs only since as I said FTMs are a cloudy matter on this point. Those are MTFs who are only, or mostly, into women, and whose reason to transition tends to rely on an internal desire to have the body of a woman.
The majority of patients in this category admitted to feeling aroused in some way at the thought of being a naked woman alone on a bed and/or by wearing female clothes or undergarments. That arousal can be conscious or not, and it can also be very mild, in that it genuinely doesn't really feel like arousal to the trans person. And those who did not and accepted to undergo a test had measurable arousal while listening to a story about crossdressing.
From what stems in an unusual sexuality (and for the majority of those who have that unusual sexuality, it will stay that way and they won't be transsexuals at all - think heterosexual ->-bleeped-<-), gender dysphoria appears and the problem becomes deeper, and the will to transition can become very strong. Autogynephilic transsexuals, although they can transition young, tend to be much older when they transition. To them passing and having a normal life tends to be much less important than "feeling like a woman".
In the past, just because their transsexualism was rooted in a sexual problem, professionals would deny those individuals transition (while it's actually just as indicated for them as for the other type as far as I know). Which led them to lie to match up their life stories to those of the "homosexual" type as much as possible. And then big bad stuff happened. Because while both types can benefit from transition, they're not the same and they don't really need the same kind of help in various fields.
For example, the post-operative regret rate in this group is higher than in the other. The likely reason is that since they all needed to lie and "embellish" their stories to receive the treatment they wanted, both transsexuals and ->-bleeped-<-s who weren't transsexuals at all ended up getting a surgery.
Now no one needs to lie to get treatment, but there are still some ->-bleeped-<- (autogynephilic) trans women who do, out of fear of what was common practice just a decade or two ago, and out of shame of their unusual sexuality.
By the way, right now the system is vastly adjusted to the needs of ->-bleeped-<- transsexuals, for MTFs, because in Western countries, they're >80 % of the transsexuals seen in clinics. Since they, yes, ultimately need the same kind of treatment, but no, shouldn't really be treated the same, compared to HSTS ("homosexual" transsexuals), that causes trouble for the latter.
It doesn't help that they fear they'll be regarded as less "valid" if they accept the idea that they're not the same, which is not the case, and as such some (a minority, but a loud one - those are the ones who'll vehemently spread not disagreement but hate and accusations about the theory) will insist strongly that there is only one big group of transsexuals, because they feel the HSTS group, generally being younger and better passing, gives them validity. While actually the only thing that joins together those two groups of transsexuals are the treatment (HRT, SRS, etc.) indicated for them to feel better, being two entirely different issues that have very different origins.
(For FTMs, it's BELIEVED that the mechanisms and types are probably the same (mirrored), but 1. the equivalent of autogynephilic MTFs is for some reason very rare thus difficult to study, and 2. to begin with, FTMs have been studied less, not sure why. That the majority of FTMs are "homosexual transsexuals" appears relatively clear though.)
Whoa. I ended up giving a pretty big description of the theory compared to what I intended. Anyway, the short version is: there appear to be two very different types of MTF transsexuals, one of which is autogynephilic, and while they have nothing to do with each other in almost every way, neither is inferior, neither should be treated as less of a woman than the other, and HRT and SRS are indicated treatments in both.
So uhm yeah. The term ->-bleeped-<- is hated, but there's hardly anything else to describe what studies show.