The Brahmavaivarta Purana is one of the eighteen major Puranas (Maha-purana) which centers around Krishna and Radha. Now Wikipedia claims that there is another such Purana available in South India with a "similar a sounding title" and similar plot.
Another text, with a similar-sounding title, called Brahmakaivarta Purana calling itself also the twelfth Mahapurana also exists, is related, but was likely revised somewhere in South India. Numerous versions of this Purana exist, in up to 274 or 276 chapters, all claiming to be either part of, or manuscripts of the Brahmavaivarta Purana or the Brahmakaivarta Purana.
So are there any major differences in the content of the existing mauscripts labelled "Brahma Vaivarta Purana" and the "Brahma Kaivarta Purana"?