The Tristar is just the Canik imported by another importer.
The 120 models are very close to the original CZ-75 design.
Apparently these have forged slides, frames, and barrels.
The Canik branded guns that are being imported are a different design, more on the order of a Glock.
They used to import the CZ-75 designed models, but I don't see them on the US web site.
Both the Canik and the Tristar name get excellent reviews by buyers, but they can use some work to make them smoother and better.
A trip to Cajun Gun Works does wonders for the CZ Tristar models, especially if you have their shorter pull trigger assembly installed.
It appears the Tristar is more available for purchase.
The finishes on these is an epoxy paint, Cerakote brand for the Tristar.
Personally, I'd prefer the all steel version S-120 that's very close to the original CZ-75.
The EAA Witness is a larger pistol because EAA went to a larger frame that will work for any pistol caliber.
The newest Witness pistols have the trendy rail mount on the dust cover and are no longer made as closely to the original CZ design, or the earlier EAA design.
You may or may not like that.
The older EAA Witness and even older Tanfoglio pistols as imported by FIE, Excam, Springfield Armory, and others were very close to the original CZ design.
The EAA Witness both older and current versions use cast slides and frames.
By some careful shopping and some gunsmithing, you can use Tanfoglio/EAA accessories like safeties and grips in the Tristar models.