Is that because the resolution on the jpeg isn’t high enough?
Jpeg is a lossy compression scheme for pixel images. There are degrees of quality, the higher the quality the closer the jpeg image will match the original and the larger the jpeg file will be, but so far as I am aware none will match the original. The differences are small, but for close examination such as here jpeg images may not be good enough. There was a thread over the weekend where someone "proved" that the Obama image was a fake because his image of the certificate looked like it had the letters OHBM in the lower left corner rather than OHSM on a higher resolution image of a genuine certificate. This too, was almost certainly an example of the problems on can see with jpeg compression.
ML/NJ