No, I can't tell you. Nobody else can either without doing an in depth genetic study on the animal. People love these questions, and you're going to get all kinds of answers depending on where you ask. You'll get...oh, that's 100% Eastern...yup, definitely a Three-toe X Florida hybrid...oh yeah, that's a Mobile, AL Gulf Coast box turtle. It's pretty funny. It's a lot like asking the different breeds contained within a mixed breed dog. You'll get as many different answers as there are people in the room. Unless you saw the Mommy and the Daddy, and they were purebred...who knows?! There's absolutely NO way to tell just by looking.
I can see that it COULD be an Eastern/Ornate hybrid. They often come out with shells appearing like Three-toes (light, slightly striated, and more round than oval), and they usually have 4 toes on their hind feet instead of the normal 3 of a Three-toe. Your animal is right in line with what I've seen. The ONLY thing that I see different from most Ornate X ______ hybrids is the lack of more heavily "armored" front legs and head (an Ornate trait). However, the picture is a tad fuzzy and hybrids are far from an exact science.
Seriously, I'd take the word of the seller. If he/she was willing to admit to the hybridization (many are embarassed or think that the animal won't fetch as high a price) then I see no reason to doubt. Of course, in the last year or so I've seen hybrids commanding huge prices. However, it's usually with more expensive turtles. Box turtle hybrids have still been cheaper than their "purebred" counterparts.
I'd be interested to see which sex this turtle turns out to be. I have a friend who theorizes that species to species hybrid turtles are always female. Of course, since most seem to be infertile, and the default phenotype is female, it would make sense.
No, not poking fun at all...I love the name Tulip!