Cap rate and cash on cash return

[Franco Epifania]

Still a little confused in these areas and would like to really understand them so i can better calculate if the investment is worth it or not. I understand cash on cash is annual net income/cash invested, but what if you are using equity from a property to invest instead of cash. I am looking at a property for 630k with a down payment of 110k using home equity. The property generates 62400-64800/year & nets 20k which if I calculated correctly yields 18%.

Cap rate I’m a little confused