If the dog barks and growls at the same time, then it is an alarm. Generally growl - it is always a sign of danger.
Barking dog can meet and greet his master. It is also trying to attract attention to his person. But then a barking sound more upbeat.
If a dog howls, the more often because she was bored and lonely. Maybe even from hunger and cold.
Animal yelps. This means that it hurts, it asks you for help.
Looking at the muzzle of the dog, you can predict its intentions. When the upper lip is raised, visible fangs, ears pointing up - it is a threat. When the dog is afraid of - dismisses the ears back or pressed to the head. The tail is short it. If the dog greets you, then it wags its tail. If it asks you to play, the dog back bends, wags its tail, raises the muzzle and eyes can read the request.