I will try to explain. My approach is anything but scientific, but based on observation.
I print on Ilford MGIV fiber. Before that it was Fomabrom 112. Whether the film is Tri-X or TMY, I always keep my paper in mind. The print developer I use is replenished Ethol LPD, which is softer working than Ilford Multigrade or Dektol.
Because this combination of Ilford and LPD takes a pretty high contrast negative to make a print I like, my negatives are developed as such.
Using Tri-X I expose normal contrast at EI 250 to get shadows off the toe a little bit. This isn't necessary with TMY so it's exposed at box speed or 500.
To match tonality of Tri-X I agitate less with TMY, normally every 2.5 minutes, which bends a slight shoulder, and Tri-X is agitated every minute.
High and low contrast lighting is compensated for by altering developer, exposure, developing time, and agitation, in order to shape negatives that fit the paper well. I ALWAYS target the print. Everything else is an intermediary and serves the final print. The negative - well I just don't think it's a good idea to talk about it unless we also discuss the resulting prints. A good film, to me, is one that is flexible enough to alter into fitting the tonality of my paper and developer. Both TMY and TX does this with flying colors, as does FP4 and Delta 100, and a few others.
So, tonality of the two films have both been adjusted to fit the paper to make prints that are highly similar in tonality.
What about grain, then? Well, if you look closely enough of course you will see a difference between TX and TMY. I sometimes make comments to provoke, to steer away from conventional thought and stimulate new ideas.
As it happens, both Xtol and Edwal 12 are solvent developers. I also use them replenished, which means there are process by-products in the solution, which helps yielding higher sharpness, finer grain, and different tonality. I lose about 1/3 stop of speed, but that does not worry me in the least. Both developers give exceptionally fine grain, and make for, to my eyes, exceptional enlargements where it can be difficult to separate one film from the other, based on how they're treated.
Xtol is awesome for subject matter with intense highlights, or where light hits the subject directly. Edwal 12 is incredible when light is flat to normal.
I hope this makes sense. It took me a couple of years to put all the pieces together, and today I have stopped using TMax, because life is easier with just one film, and in 35mm there is a toss up between the slightly smoother tonal transition of TMY compared to a slightly more interesting texture that TX yields. I could go either way.