What is the difference between the NYNJA economy and the NYNJA coin?
I will use an excerpt from the white paper to answer your question
The “NYNJA Economy” (or “Platform”) is expected to facilitate an ecosystem of freelancers and sellers of goods and services.
While
NYNJACoin is an Ethereum-based token which follows the ERC20 standard. NYNJACoin will be accepted as payment within NYNJA App for goods and services.
Or rather it might be best that you check the white paper.