The coronavirus death rate is calculated based on confirmed cases, i.e. cases that are so severe they require medical attention. It's estimated that 80% of cases are asymptomatic. Total flu cases are estimated, for example a total of 35 million CDC estimated infections in the US in 2019 versus 8 million coronavirus cases. That obviously brings the death rate up by a factor of 4. Coincidentally your posted death rates are 0.63 versus 0.15. Or roughly a difference of 4.