The term, "kingdom of heaven" is only used in the gospel delivered according to Matthew's major purpose of describing Jesus Christ as the "Lion of Judah" from Abraham and through David who will reign "on earth" on David's throne as the Jewish King of kings. Luke also describes Jesus as being the "son of man" with lineage going all the way back to Adam through Seth.
Jesus is that very WORD of God who became a "man" on earth under the firmament--not in heaven above the earth. Notice that the parables concerning the kingdom of heaven always show an earthly context--not a heavenly one (sower, field, harvest, weeds, great tree, etc.)
The Kingdom of God, on the other hand, is a spiritual kingdom--without observation. John's mission was to describe Jesus as having the face of an eagle--the king of the fowl of the air. Mark described Jesus as having the face of a calf/calf of an ox--servant of both God and man.
The great tree, amazingly, is revealed as growing up out of the earth so that even the fowl of the air may rest on its branches. Trees are earthly--of the earth. Those fowl of the air speak of the resurrected sons of God who will return with Jesus when He returns to rule among His greatly loved people of Israel in that Day-of-the-LORD earthly rule from Jerusalem over all the nations of the earth. The Jews will be given the "rest" that he promised them, and the church will be given their "rest" in the branches of that Jewish earthly kingdom. The spiritual sons of God (church) will not be servants of the resurrected "son-of-man" King of kings at that time, but rather will rule with Him also as resurrected men during Israel's promised rest.
A great question that might yield answers of further proof of these things might be, "Why did the earthly tabernacle and earthly temples (dwelling places of Messiah) have creatures having only two faces--a lion and a man--overlooking God's earthly covenant, whereas the creatures in God's heavenly dwelling place had four--the lion, the man, the calf, and the eagle. I'll leave that one to someone else to ask if anyone is interested.