The term, 'kingdom of heaven' is almost but not quite the same as that of 'kingdom of God'.

.................Both terms are generally interchangeable, but 'kingdom of God' relates to God's kingdom as it is throughout the universe.

...........................'kingdom of heaven' is restricted to events on earth, which represents commonly called Christendom.

.................The kingdom of heaven [please read] in Matthew 13:47-48 is said to have both 'good fish' and 'bad fish' in it.