Emoji fragmentation of a small stakes, culinary variety.
Apple—which is in the process of rolling out new unicode 10-compliant emoji—opts for a relatively photorealistic style, putting the lettuce underneath the patty but the tomato and cheese above. By contrast, Google keeps the vegetable garnishes up top where they ought to be, but the company puts the cheese underneath the patty.
Shortly afterward, others began to note a wide variation in burger construction across different emoji implementations. WhatsApp is alone in including ketchup. HTC's design team went for a double patty approach with some visual separation courtesy of what we must assume is rather wilted lettuce. Mozilla's approach is the most bare-bones, backyard cookout style, with nothing to adorn its burger save for a slice of cheese and some sesame seeds on the bun.
A little digging in Emojipedia reveals plenty of other variations in the way emoji show up across different platforms. In addition to its burger-building faux pas, Google's emoji designer also needs a refresher course on how beer works, because a foam head can't sit on an airgap. There is little standardization among the taco emoji, either—Apple's looks the closest to something I'd actually want to eat, while Microsoft's resembles an 8-bit video game dinosaur as much as it does the Internet's favorite street food.