There is no difference between a blocklist and blacklist, and the terms are often used interchangeably across the email industry.
Over the years, industry leading blocklist providers such as Spamhaus, Spamcop, Barracuda, and Validity decided to use blocklist instead of blacklist.
Blocklist directly reflects the technical or functional mechanics related to identifying potential sources of spam and the actions (block, filter, or allow) a mailbox or filtering provider may take when processing incoming email.
