Bulk API operates in terms of a two-tier system of containers to track units of data movement work. Each tier is described here:
Batch—A batch is a set of records to be imported. The records are represented in CSV or XML format. For import jobs, a batch cannot exceed 10,000 records. Batches are not applicable to export jobs, which use result files that cannot exceed 1GB.
Job—A job is a list of batches. The job specifies the type of operation that will be performed in the batches, such as insert or query.
Bulk REST API calls ...