Both the polymers have a repeating structure which is the basic definition of polymer.

All Plastics are the polymers but all the polymers are not the Plastics, why because there will be biodegradable polymers, biopolymer, rubber exist, which will be not in the plastic group

Polynucleotide is a molecule that is usually in DNA and RNA. It is biopolymer composed and usually has thirteen or more nucleotides.

The DNA double helix contains two coiled biopolymer strands. The double helix was discovered by James Watson and Francis Crick.

Lignin is a biopolymer that gives support to vascular plants, and is thought to have evolved after aquatic plants took on land. many aquatic plants produce lignin or lignin-like polyphenols however. There is still debate on distinguishing terrestrial from aquatic plant lignin.