When I think about it, I have never seen a tree marketed as a Chinesse elm.
This is how a Chinesse elm could look like:
And this is how the leeves of a Zelkova Zerrata could look like:
Even though they look very similar, there are differences between them. But it could be difficult to see them if you dont have anything else to compare with.
The Chinesse elm /Ulmus Parvifolia is often darker in the trunk than the Zelkova Zerrata.
But you can find almost anything marketed as anything else.
Please follow this link and you will find a Ficus Retusa marketed as a Ulmus Zelkova indoor plant, at Ebay!!!!