That is a very broad question and there is no easy answer. Some mines put out both: Variscite and turquoise. It is, in some instances, referred to variquoise. I believe Jim Saunders owns the Damele mine now. According to him, Tony Cotner (former owner of Paiute mine, Damele mine, etc.) could tell the difference visually.
The variscite that I own (that came from the mine owners for validation purposes) tends to have a more ‘glassy’ look. Of course, it is dependent upon the final polish as well. Colors (very light green to a yellow) tend to dominate the pieces I have seen.
Also, in general, the variscite tends to have a more nodular look. As if there were layers built upon layers. If you have ever had a jaw breaker with different colors on the inside and if you lick through you start to see the underlying colors? Similar to birds eye, but more pronounced if that makes any sense.
Here is a great article on it:
I will try to post pics later.