Matthew, for some strange reason, is the only one that refers to the Kingdom of Heaven. It is mentioned no other time in the New Testament. The Kingdom of God is used the most in the New Testament, which is in 10 different books.
Matthew’s Gospel is of a Jewish nature usually, which is probably why he used it when Jesus was likely saying Kingdom of God. Matthew had done “Heaven” instead of “God” in the phrase “Kingdom of God”, because it was out of respect for the Jews (who were careful to use God in everyday speech). He would have either wanted to state “Yahweh” or “Heaven” when explaining the Kingdom of God.
This was really a problem for a context of verses, where Jesus using Kingdom of God and Kingdom of Heaven interchangeable in Matthew 19:23-24. To say Jesus really meant the Kingdom of Heaven and then in the next verse say Kingdom of God would make Jesus look like a liar, in which He is not. This would mean that the Kingdom of God and the Kingdom of Heaven are the same meaning.
Comparing parallels will reveal the truth: Matthew (Mt) 11:11-12 to Luke (L) 7:28; Mt 13:11 to Mark 4:11 and L 8:10; Mt 13:24 to Mark 4:26; Mt 13:31 to Mark 4:30 and L 13:18; Mt 13:33 to L 13:20; Mt 18:3 to Mark 10:14 and L 18:16; and Mt 22:2 to L 13:29.
In most of those instances, it’s two against one, and two witnesses are better.