They were nearly wiped out by disease and in mass killings and other horrific crimes.
Archived version: https://archive.is/newest/https://www.straitstimes.com/asia/australianz/truth-telling-inquiry-finds-australias-indigenous-people-faced-genocide
Disclaimer: The article linked is from a single source with a single perspective. Make sure to cross-check information against multiple sources to get a comprehensive view on the situation.
I would disagree on Spanish being less genocidal, just a different flavor of genocide. More focused on erasure of cultural and religious elements that comprises a distinct group compared to the targeted killing and displace style of genocide.