There are two key differences between Peak and Arafura.First is...

There are two key differences between Peak and Arafura.

First is that Peak is currently focusing on a rare earth concentrate, rather than refining all the way to metal (or metal oxides, carbonates, whatever - point being that all the different elements are essentially separated). There's a lot more value in having separated rare earths than in having a mixed oxide. Capex is significantly higher to get there, but the return is proportionately greater as well. Yes, Peak is talking about a refinery as well; but that's a long way after production starts. The share market won't price that in unless and until the plans become more concrete.

Second is that Arafura's resource is in Australia; the perception - right or wrong - is that Australia's regulatory environment is a safer one than Tanzania. Note that I'm being careful in talking about the perception, rather than the actual reality (which I really cannot judge in a meaningful way). That's going to be a significant depressor on the company value until the company is actually up and running as a going concern.

Take both of those into account, and a comparison based on Arafura's market capitalisation is premature at best, IMO. Don't get me wrong, I'll be absolutely thrilled if your predictions come to pass. I simply don't think that they're likely, or even plausible.

Just my two cents' worth, coming from some random on the Internet.