Different environments require different types of tags. For example, inventory management on a construction site will need a robust, likely waterproof tag whereas a computer lab may just need a  basic label.  Tags may be as small as a grain of rice or as large as a brick. Some are flexible, some are rigid but all offer similar fundamental technology.

Of course, tags have a lot of variation in terms of performance, storage and power requirements.  Smart labels are extremely thin contactless devices typically used for single or minimal use applications. Other types for repeated or semi-permanent use are often encased in tough materials designed to withstand the elements. Tags are often reusable and suitable for lifetime identification which gives them a significant advantage in terms of cost over labels and barcodes. The downside being labels are much easier to attach.

Radiofrequency fobs come in either active or passive format.  Passive tags receive their operating power from the radio waves transmitted by the reader and active tags need a battery to power their transmissions.  Most logistics operations are satisfied with passive tags. which are far cheaper and more convenient.  Active tags are really only used when its important to have a long read distance for the tag.