Face Grain is probably what most of us think of when we talk about wood grain. This is the patterned, dark and light lines we see when looking at wood. We see it every day in wood floors and table top surfaces. When looking at a typical hardwood floor, or even fake wood floor, we are seeing the face grain. The different colored striations are actually the growth rings of the tree, just seen from the side. The darker stripes are often smaller, and develop when the tree is in the Fall and Winter months. The lighter stripes are generally larger and reflect the better growing period of the Spring and Summer months. The pattern of this grain reflects the way the wood was cut into lumber, but we can get into that another day.
End Grain is when you are actually looking at the growth rings of a tree, such as a stump, when you are able to count the seasons that tree has lived. End grain is like the top of a bundle of straws. It is the most porous part of the wood and absorbs the most moisture. Hey! this is why we see the ends of boards painted in the big lumber stores. They paint them with a latex paint, to slow the amount of moisture absorbed while waiting to be purchased. The endgrain will also absorb more of the protective finish that is applied. This will lead to the endgrain having a darker color than the face grain. End Grain doesn't have much in the way of pattern and is sometimes hidden because of this. Generally,you will not find endgrain on plywood furniture. The edgebanding that is used to cover the sides of plywood is mostly manufactured in face grain, though there are endgrain options as well.
The most common household example of End Grain is a cutting board or butcher block. End grain is used for a reason! Think about the bundle of straws analogy, but imagine the straws microscopically thin and hard. Now imagine someone splitting logs for a fireplace. We bring the axe down where we can see the rings and the wood splits. This is splitting the straws into bundled sections, its easier to push the straws apart, instead of cutting them into smaller straws. This applies to your knife as well. As you cut through your vegetables on an endgrain cutting board, the thin knife edge finds its way in between the bundled straws and slightly pushes them apart.
Looking for pattern continuity from the face grain to the end grain is one of the easiest methods to tell if you are looking at edgebanded plywood or a true hardwood top.