Rayon is different from truly synthetic fibre because
it is obtained by chemical synthesis of cellulose.
Rayon is a semi-synthetic fibre because it is produced by the chemical synthesis of cellulose present in plants. It has a silk-like appearance and due to this, it is also known as artificial silk. Moreover, its fibres can be woven like those of natural fibres.
Rayon can be dyed in a wide variety of colours but this is not the characteristic that made it different from synthetic fibres because synthetic fibres like nylon and polyester can also be dyed.