Ballista started out as a separate project and was donated in April 2021. They currently share a release schedule (but have different versioning) and this was the first release of DataFusion to include the Ballista crate.
My hope is that Ballista and DataFusion become more integrated over time but remain separate, with DataFusion being an embedded / single-process query engine and Ballista providing distributed execution.
My hope is that Ballista and DataFusion become more integrated over time but remain separate, with DataFusion being an embedded / single-process query engine and Ballista providing distributed execution.