Viṣṇu is a part, but Kṛṣṇa is the whole. This is the verdict of the Vedic literature. The Brahma-saṁhitā (5.46) gives the example of an original candle which lights a second candle. Although the candles are of equal power, one is still accepted as the original and the other is said to be kindled from the original. The Viṣṇu expansion is like the second candle. He is as powerful as Kṛṣṇa, but the original Viṣṇu is Kṛṣṇa. Brahmā and Lord Śiva are obedient servants of the Supreme Lord, and the Supreme Lord as Viṣṇu is an expansion of Kṛṣṇa.
After describing the līlā- and guṇa-avatāras to Sanātana Gosvāmī, Lord Caitanya explained the manvantara-avatāras, incarnations associated with the Manus. He first stated that there is no possibility of counting the manvantara-avatāras. Fourteen Manus appear in one kalpa, or day of Brahmā, and for each Manu there is a manvantara-avatāra. It is calculated that each day of Brahmālasts 4,320,000,000 earth years, and Brahmā lives for one hundred years on this scale. Thus if fourteen Manus appear in one day of Brahmā, there are 420 Manus during one month of Brahmā, and during one year of Brahmā there are 5,040 Manus. Since Brahmā lives for one hundred of his years, it is calculated that there are 504,000 Manus manifested during the lifetime of one Brahmā. Since there are innumerable universes, no one can imagine the totality of the manvantara incarnations. Countless universes are produced by the exhalation of Mahā-Viṣṇu, and thus no one can begin to calculate how many Manus are existing at one time.