When basic sugar (or sucrose) is inverted, it is broken down into the two basic elements that make it up: glucose and fructose. Inverted sugar syrup is produced either unintentionally, by adding specific ingredients to a recipe, or intentionally to make a sugar syrup that has many advantages in baking.
Larger sensors are the reason that 8 megapixels from a digital SLR camera (or 5 or 13) best those 8 megapixels from a smartphone camera. You get roughly the same number of pixels, but the pixels on the dSLR get to be larger, and therefore let in more light.
It looks like HD+ is 1600 by 900 resolution. FHD is 1920 by 1080 resolution. So the FHD will put more data on the screen, but text will be smaller. Whether it is worth the difference is up to you. Obviously some people do, otherwise Dell would not be selling the FHD models. Obviously some people do not, otherwise Dell would not be selling the HD+ models. Your money, your choice.