Taurus and Rossi use softer metals and less hand fitting of critical parts. Also, S&W has a "Lifetime Warranty" and their customer service is "top notch" IMHO.
Total BS. Rossis and Tauri are just as good METAL. Might have been true 25 years ago, but not now. Frankly, I have a 25 year old Rossi that's impressive compared to the M88 I bought in the early 90s. The finishing steps get passed up on the Rossis from the ones I've owned, a few of 'em had some tool marks here and there like under the hammer where my M88 was pretty rough. But, Taurus, I can't tell the difference in it an my old M19 other than I like the design better on th eTaurus. The trigger is slick, it's more accurate, it doesn't have that stupid flat spot at the bottom of the forcing cone that cracked on my M10. It's just as high quaility as any Smith or Ruger I've ever owned, though I tend to love the Ruger's side plateless, very strong design and simplicity of disassembly compared to the Taurus.
I'll put my Taurus 4" 66 against any Smith as a shooter. Rossis, well, they work on a budget, but you get less gun in fit and finish and the DA trigger is usually a little rough, but they work and I've never worn one out. I put probably 15K rounds mixed .38/.357 through my old M971 and it was still tight as a drum when I traded it in a partial trade for a .45 Colt Blackhawk which I do like better.
. I made a good deal and traded up.
Taurus and Rossi has the lifetime no bones warranty, but from what i've heard about customer service, be prepared to wait a while. Smith and Wesson has 'em there. It's due to the corporate arrangement at Taurus as I understand it. Some don't complain, some whine like five year olds when their gun is gone over 2 weeks. I have not had the occasion to use it, though.