piaco asked: Rules-wise, is there a practical difference between colorless mana and generic mana, or is "generic mana" just a slang for "mana of any kind"?

Colorless mana is mana that has no color. It is a type of mana.

Generic mana is a cost which can be paid for using any mana including both colorless mana and colored mana. It is a type of cost.

The two get confused because we use a number in a mana circle to represent both.

Take the Sol Ring that’s been printed in Commander decks. The 1 in the mana circle in the upper right corner is the mana cost of the card and it is a generic mana cost in that you can spend any color or colorless to pay for it.

The 2 in the mana circle in the rules text is a type of mana it produces which happens to be two colorless mana.