The Pietta faithfully copies the original Colt internal design. THis means it uses flat springs for the trigger and bolt return and hammer mainspring. And I'd have to check again but I THINK it uses a pin and small coil for the hand... which is a nice improvement over the small leaf style hand spring which tend to break too easily.
THe Rugers do not faithfully copy the original Colt design. For some, me included, this matters.
I'm willing to live with some risk over the durability of the Pietta compared to the Ruger to get the proper Colt 4 click cocking action and having to use half #### to unlock the cylinder for loading. YMMV on this count obviously.
The main spring is pretty bullet proof but the flat trigger and bolt springs tend to snap for some folks. But so far mine are fine even after about 1200'ish rounds per gun down the pipes over the last two years. The good fix is to replace them with the wire spring option sold through various dealers either when or before they let go if you're worried.
I think it's fair to say that the Vaquero is a superb and stout gun which will last literall for years and ask nothing more than the occasional cleaning. The New Model Vaquero is a slightly lighter frame scaled down to more accurately reflect the size of the orginal Colt 1873.
As for longer term durability I've seen some say on various forums that none of Italian clones or even the New Model Vaqueros will stand up to a steady diet of Magnums. Not that they'll blow up or any such thing. Just that the constant pounding of full house magnums will tend to shoot the guns loose sooner than when used with a more regular diet of .38Spl with some magnums. Other's say that even the NM Vaquero would happily shoot a steady diet of Magnums without issue. I'm not sure where the truth lays on this.
For the Pietta I don't doubt that it would suffer some premature aging if I shot lots of magnums. But then it's a gun at a lower price. I'm more than happy with mine and they are holding up to my cowboy shooting just fine. More than that I can't really say without a crystal ball.
The old original Vaquero, on the other hand, is basically the Blackhawk with fixed sights. The sturdy nature of this bigger and more solid gun would laugh at a steady diet of .357 full power magnums. My buddy shoots CAS with a pair of the old Vaqueros and to see my Pietta and his Vaqeuros side by side is enough to make one wonder how his guns grew up so much bigger....

Durable for the old Vaqueros should be part of their name.