APPICs is an entirely different platform so their content will differ from Steemit. And each SMT can program their blockchain differently so it will differ slightly from Steemit. For example, some rewards will go back to the company for application costs. But there are a lot of different parameters they can program which will make them unique.

And you would want the APPICs coin if you're going to be using APPICs. Just like with Steemit, you need Steem to function on the blockchain. But if you're not going to be using APPICs, then the only reason to have the coins is as an investment.