I took these photos when I was Denver about 2 months ago. The label on the pot stated "Rhoeo tri-color. Is this rhoeo tri-color belong to genus Tradescantia, spathacea species? Or they are two separate genera?
I think the new/preferred name is Tradescantia spathacea (supercedes Rhoeo spp); in your case cv. 'Variegata'.
Yes, as far as I have been able to tell. Tradescantia and Setcreasea are synonymous.
Tradescantia spathacea was formerly Rhoeo discolor, the plant with long straight leaves and white flowers, uploaded by vngarden first. The leaf clusters generally arise from single dense base.
The second upload by vngarden with smaller leaves usually longer stems and larger purple flowers was formerly known as Setcreasea purpurea. It is now Tradescantia pallida.