Those at the top get things such as food, resting places, mates and favored possessions preferentially over lower ranking individuals. This is dominance hierarchy. The rank of an individual is determined by such factors as genetics, who was first on the territory, age, results of competitive encounters, and the competition for resources. In an encounter where one animal acts dominant there needs to be another who acts subordinate or fighting will occur. Subordinate or submissive behaviors include looking away, or lowered head, body, tail and ears.
Extreme submission is shown by crouching down and rolling over and exposing the abdomen.
Note that a dominance or pack hierarchy will develop in a group of dogs, but that dominance or leadership refers to the relative relationship of two individuals. Whether a dog is subordinate to one dog or person, has little bearing on whether that dog is subordinate to another person or dog. Dogs have evolved from wolves, who live in groups, so they are evolutionarily prepared to live in a group. In most cases they are ready to accept a leader . You may have little control over which dog in your home becomes leader.