Are bulk processing URLs returned in the same order as submitted?

No. The Bulk API/Bulk Processing service simultaneously extracts data from multiple pages at once, and indexes the data as it is returned from Diffbot APIs.

Because many factors enter in to when data is successfully returned — among them the speed of a site’s response, the need for retries if a site returns a temporary error, and the potential for incorrect or invalid URLs — there is no reliable order to the output of a downloaded CSV or JSON result set.