What does Krishna mean?
From Sanskrit krishna (कृष्ण), literally 'black, dark, dark-blue'. It is the name of the eighth avatar of Vishnu, the beloved deity of the Bhagavad Gita and Mahabharata, so the name is first and foremost a divine name.
What does Kunal mean?
From the Sanskrit कुणाल (kuṇāla), usually glossed as 'lotus' and secondarily 'a bird with beautiful eyes' (the latter a folk etymology). Historically the name of Emperor Ashoka's son Kunala, 3rd century BCE.