When I resized the photograph to this image in my image viewer, I see enough differences to make me feel this was genuinely made with effort and not just some lame Photoshop filter. Most telling is the shape of flower and the background. Less obvious is her eyes are bigger, her nose is smaller, her lips are different shaped, and the shadows on her shoulders are noticeably different from the photograph. Compare the strands of hair on her shoulder between the two pictures and note how different they are.
I suppose he could have used the original image as a base layer and then painted over it, instead of a traditional side-by-side painting. That said, he could have merely resized the various elements I mentioned above and then applied some filters, then retouched a few places with a brush. I'd hope that is not the case, but then anything really is possible with photo manipulation software today.