You're mixing two different kinds of inequality here, The top graph is wealth (aka savings), while the bottom one is income. Wealth is the much harder one to crack, and Sweden actually has much higher wealth inequality than all of the other countries being compared.

It's worth noting that one of the main reasons that Sweden has relatively equal income before tax is because of the way the tax system works. Because social security contributions cap out at ~$70k/year, similar to the US, but there is no similar cut off for social security payroll taxes, employers generally pay their employees in dividends and private pensions instead of income, above that $70k level. Taxes are generally flat in Sweden, though.

- a swede