An Asset represents a unique virtual or physical product in your businesses. Assets should been seen as unique (physical) objects. They represent the actual unique product that a specific customer dan own. For example a washing machien with a specific unique serial number. Or some key card ID that exists only once.
Where a Product represent an SKU for a whole product group. An Asset means the actual instance of a Product that is owned by a specific customer. An Asset is usually identified by a serial number or some other unique number engraved on the product or hardcoded into the product's firmware.