To me, ransomware attacks are specifically "the malware got in and turned all my data to mush; the attacker doesn't care about my data, just that I'll pay to un-mush it."
This is "the malware got in and sent copies back home; now home base is threatening release and expecting payment to prevent it." To me, this is blackmail done via hacking, not ransomware.
Fwiw, many actors doing the former are also doing the latter. If someone paid you once to unencrypt, presumably they'll pay you again to not disclose the data. The line between those two business models is pretty blurry.
This is "the malware got in and sent copies back home; now home base is threatening release and expecting payment to prevent it." To me, this is blackmail done via hacking, not ransomware.