Kṛiṣhṇa, God, the Supreme and absolute Person, is the Lord in his personal, primordial and original form. The original Lord, Krishna, appeared in Navadvīpa (India) in the guise of Chaitanya Mahaprabhu. He is the source of all Avatars, and appeared in person in the form of Chaitanya Mahāprabhu. Thus, Lord Chaitanya (or Caitanya) is the Supreme and Absolute Truth.

Lord Chaitanya Mahaprabhu is God, the Supreme Person. He is indeed Krishna, the Supreme Lord.

The sages call him Lord Chaitanya Mahaprabhu, Lord Caitanya Mahaprabhu, Lord Krishna Caitanya Mahaprabhu, or Lord Krishna Chaitanya Mahaprabhu.

Caitanya means: Active Force, Conscious, Knowing.

Chaitanya means: Pure Consciousness, Vital Principle.

Krishna Caitanya means: All-living seductive force.

Krishna Chaitanya literally means: whose consciousness is Krishna.

Lord Chaitanya Mahaprabhu, who is in fact Krishna Himself, came to earth 500 years ago as a very great sage, a great Pure Soul, a great Devotee of God, to teach by example to the human beings the path of spiritual realization proper to the age in which we live, namely the Sankirtana the hymn, the song of the Holy Names of God.

In the Iron Age, the one in which we are now living, the Lord incarnates to teach the chanting of the Holy Name of Krishna. Putting on a yellow complexion, He personally shows people how to love God through the chanting of Krishna's name and Himself manifests his love for God through song and dance, surrounded by thousands of people who follow him. The advent of this Avatar of the Supreme Lord is specifically predicted in the pages of the Srimad-Bhagavatam, Words of Wisdom, (11.5.32), where it can be read that in this Kali Age or Iron Age, the Lord is embodied as a devotee who sings incessantly:

Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare / Hare Rama, Hare Rama, Rama Rama, Hare Hare.

Lord Chaitanya Mahaprabhu appeared to spread the chanting of the Holy Name, spread the love of God and bring fallen souls back to Him.

Krishna had said: I will appear in the holy land of Navadvīpa as the son of Śacīdevī. (Kṛiṣhṇa-yāmala)

When in the age of Kali, (the iron age, the present age), the time comes to begin the movement of saṅkīrtana [Any activity which aims to spread the glories of God for the benefit of all. Its main manifestation is to sing in public the song of the Holy Names of the Lord, always accompanied by dances and distribution of consecrated food.], I appear as the son of Śacīdevī. (Vāyu Purāṇa)