The Dogwood family has many members some of which grow on practically every continent on earth. They can range from entirely insignificant to stunning beautiful such as Cornus Midwinter Fire and from very small to decent sized trees.
Telling a dogwood is easy (provided it is in leaf). Look for plants that are generally shrubby and that have spear-head shaped leaves. Take a leaf and gently pull it "across the grain" (so you are pulling the tip of the leaf directly away from the stalk. Just as it splits, look to see if the veins in the leaf remain unbroken - they look like threads bridging the gap. If they do, you have a dogwood.
Congratulations, but so what. Well if you happen to be stranded and have to fend for yourself, dogwoods are useful friends. That same stringiness in the leaf applies to the bark. Strip it lengthways and plait or twist it and you have a strong cord to use in snares, tying tent poles together, making fish traps etc.
You will also notice, that the young growths of dogwoods are very straight. And if you try to burn them, they just smoulder. Which makes them great as kebab sticks over an open fire - when sharpened at one end... with your flint knife of course.