Main ones for non-technical folk:
Content Creator - With any crypto you can make money through price appreciation. STEEM is unique in that you can make even more without selling your crypto by simply creating content. And you get to grow your global audience at the same time, which may lead to other paid creative opportunities. The more you invest in STEEM, the faster you will gain traction on the platform with your content.
Not a Content Creator - With any crypto you can make money through price appreciation. STEEM is unique in that you can make even more without selling your crypto by simply loaning the use of it to content creators on the platform. Ownership of your coins always stays with you, but they pay you between 15-30% interest just for using the power of your holdings to be more successful on the platform with their content.