These refer to the same being. You may have to use the same word to translate both.
## he had fasted ... he was hungry ##
These refer to Jesus.
## If you are the Son of God, command ##
This can be 1) a temptation to do miracles for his own benefit, "You are the Son of God, so you can command" or 2) a challenge or accusation, "Prove that you are the Son of God by commanding" (see UDB). It is probably best to assume that Satan knew that Jesus is the Son of God.