I'm thinking of a globally diversified portfolio of index funds based on modern portfolio theory.

You can read about the investment strategy, but basically it comes down to risk adjusted returns over long periods of time.

It will become abundantly clear why Pokemon cards are not part of that strategy.

We probably have different definitions of active investing. I take my definition from Wikipedia: https://en.wikipedia.org/wiki/Active_management

In my mind, another way to divide the two is about assumptions about efficiency. Passive investors assume that the market is generally efficient, and do not try to exploit inefficiencies to generate returns. Active investors generate returns from perceived inefficiencies (information asymmetry, etc).