Am I correct Delta 400 has a contrastier look then TMAX 400?
Sensitometric Contrast depends on development.
Spectral response may be slightly different so you may require an slightly different filtration to get the same "contrast look" for a certain subject.
with TMAX 400 being smoother -cleaner in look?
D400 has slightly more grain than TMY, but developer/dilution is also a factor, for MF and up you won't find much a difference, for 35mm is easier to see some difference.
TMAX 400 seems brighter as well. Delta 400 pictures have a darker rendition then TMAX 400
It all depends on exposure, filtration and printing, with both you may obtain similar results.
Even though TMAX 400 is said to be the sharpest film for its speed, because of the contrast on Delta, Delta looks sharper?
Both are excellent films, sharpness and "sharp look" is more about your skills, right illumination is first, then lens best aperture and shake abscence. If you shoot handheld then shake is always the important factor, you may use a monopod.
How are you finding these two films comparing?
I feel TMY has greater highlight latitude for the extreme overexposures, but reaching high densities in the extreme highlights that are difficult to print optically.
Also would Delta 400 look a lot more like Tri-X, other then grain size?
Not only grain size, grain structure. TX has a unique look with grain being most evident in the shadows, delivering a "dramatic" look. Instead HP5 delivers peak grain in the mids, a different classic aesthetics. Delta 400 is not about grain...
TX is long toe, so its roll-off in the shadows has that nature, D400 is more like TMY in that concern.
___________________________________
Do this, take a D400 roll and a TMY roll. With both make exposure bracketings and filter bracketings, compare.