Is there a preference between the two? I always thought they were the same, but I cant find a detailed explanation stating whats the difference, I thought it was just a variation,
They are two different species. I know who your talking about and I don't know why his pictures of tiger and zebras look the same probably because he imports them and doesn't know exactly what he has. Also his shrimp are all wild caught so I would suggest getting captive bred as they will adapt much better.
Here is a picture of one of my Striped Indian Zebra Shrimp. There is a non striped variety as well that looks like the second picture. The color of the body on the NS variety can vary from tan to almost black. The last picture is a couple of my tiger shrimp with a baby in the foreground.