“Kingdom of God” and “Kingdom of Heaven” are referring to the same thing. Even though some argue that there is a difference especially in the book of Matthew, a close study of the bible in its entirety reveals there is not difference. “Kingdom of God” is a reference to the kingdom in relation to who the King is, that is God but “kingdom of heaven” is a reference to the kingdom in relation to the territory or domain which is heaven. But you would agree with me that the Kingdom of God is far bigger than just heaven it extends to earth and beyond.
Consider Jesus’ use of the phrases in His discussion with the Rich Young Ruler in Matthew 19:16-24.

23 Jesus said to his disciples, “Truly I tell you, it will be hard for a rich person to enter the kingdom of heaven.
24 Again I tell you, it is easier for a camel to go through the eye of a needle than for a rich person to enter the kingdom of God.”