"1. adjusting for population difference it's still a very very sizeable difference"
In 1955, experts had estimated, on the basis of qualitative assumptions, that 200,000-1,200,000 illegal abortions were performed each year.
That's the closest data I could find to the holocaust.
And using your research that "11 million died in the holocaust, over the course of several years."
Since the holocaust lasted 12 years, that's about less than a million killed annually in the holocaust. That's overall just as much holocaust deaths to abortion deaths in America annually.
https://www.guttmacher.org/journals/psrh/2003/01/public-health-impact-legal-abortion-30-years-later
https://www.museumoftolerance.com/education/teacher-resources/holocaust-resources/timeline-of-the-holocaust.html
"2. What matters more? Percentage of population killed? Or individual lives lost? Just saying"
Depends. But in this case the individual lives lost. I just gave you some stats