What's the difference between Powermine and gTokens?

Looks like Growth DeFi has 2 kinds of tokens: PMT — which I gathered is Powermine tokens...hopefully... — and gTokens.

Tons of questions from my side:

1. What's the difference?
2. How does this dual system allows for higher yields?
3. How do I go about gettinng leveraginnng this? Or in other words: which token should I buy and what do I do next?