Buddhism keeps the name Brahma but empties it of creation. In the Pali canon 'Brahma' is a rank of deities in the form realm, long-lived but not eternal and not the makers of anything. Two suttas show what this means. In the Brahma-nimantanika Sutta, Baka Brahma is sure his heaven will last forever and that he himself cannot die; the Buddha goes up to him, argues him down, wins a contest of disappearing, and pronounces him covered in unwisdom. In the Ayacana Sutta the roles are reversed in another way: after the awakening the Buddha is inclined to stay silent, and it is Brahma Sahampati, the senior of the great Brahmas, who descends to plead with him to teach. The creator of the Puranas has become first a deluded god and then a suppliant.
The Vishnu Purana and the Bhagavata absorb the Buddha the other way round, as a form Vishnu took to delude the enemies of the gods; Jayadeva's Gita Govinda later recast the motive as compassion for animals.
What is different here:
The Buddhist texts demote Brahma; the Vaishnava texts absorb the Buddha. Each tradition frames the other's central figure from inside its own scheme.
Sources: Brahmā (Buddhism) — Wikipedia; Mahabrahma — Wikipedia; The Vishnu Purana: A System of Hindu Mythology and Tradition; Dashavatara — Wikipedia; Why is Buddha listed as an avatar of Vishnu?