Tags are IoT sensors that collect data about the specific object to which a tag is attached. Commonly used in supply chain management, ID badging and access control, tagging involves sending data using specific radio wave emissions.
An active tag is powered using internal battery, where a passive tag gets energized using a the power from a tag reader.
RFID (Radio Frequency Identification) can be used to receive and transmit radio waves over distances of 100 metres or more (for active tags, equipped with their own battery), NFC (Near-Field Communication) is limited to no more than 20 cm in the best cases. In reality, NFC's range is more like 0 to 5 cm.