An income tax is a tax on a flow. That's the money that's moving into people's accounts. A wealth tax is a tax on a stock. The wealth tax that has been proposed would really affect the 1% of the 1% but generate tens of billions of dollars in revenue. That in and of itself wouldn't reduce inequality that much, but where you could start reducing inequality with those funds would be by providing greater supports at the bottom of the hierarchy.
A wealth tax is a way to get wealth that has become locked into the accounts of the ultra-wealthy moving through the economy again. Our financial assets are supposed to do good for us by moving through the economy. Instead, they get stuck, and that contributes to the excessive power of the ultra-wealthy.