RapidNFC generally call items like hang tags, keyfobs, disc tags and so on 'NFC Products' and generally use the term 'NFC Tags' only for stickers and inlays. (More information on the difference between stickers and inlays can be found on these pages.)Products come in a range of different shapes and formats and can be made using different types of antenna. For example, the keyfobs usually use a coil of wire as the antenna (which we call an e-unit).
NFC Tags (stickers and inlays) are constructed by attaching the NFC chip to a small antenna, usually made of very thin aluminimum. This is fixed to a plastic substrate (thin sheet of plastic) to keep it together. The variation of tags arrives partly in the size and design of the antenna itself but also the construction of layers of plastic and adhesive that make up different types of tag.
Aside from the choice of NFC Chip, your choice of NFC tag also involves size, construction, antenna and an optional layer so it can be used on metal.
Here's some information to help you decide !