Currency is a coupon for money.

Money is a Non-Consumable asset.

They are related but not the same.

When you accept bitcoin for an item, unpon confirmation, that transaction has final settlement.

When you accept lightning for an item, you must then close the Channel, and await confirmation to "Own" that Bitcoin. Then the transaction has final settlement.

That is the difference.

Put another way, if I give you a chicken, you have a chicken.

If I give you a coupon redeemable for a chicken, you do not have a chicken.