I often use JPEG images, and I have noticed that there are two very similar file extensions: .jpg, which my mobile’s camera and the Preview application use, and .jpeg, with which Image Capture saves the images from scanning with my Canon MX455 printer. LaTeX doesn’t seem to distinguish, as I gave it a .jpeg with the extension changed to .jpg and the result seems to be the same as if it had been a .jpg right from the start. I have wondered what the difference between the two is. I have come across this question, and will certainly read through it, though at the moment I’m slightly out of time. However, from what I saw giving it a quick look, it seems not to distinguish the two extensions. In fact, it seems the file type’s name is JPEG and the file extension is .jpg:
JPEG (or JPG, for the file extension; Joint Photographic Experts Group)
(excerpted from the first answer there). So is there any big difference between the two extensions? And if so, what is it?