Homopolymer - If only one type of monomeric unit takes part to form a polymeric structure, it is called as a homopolymer.
Example = Glycogen, starch, chitin
Since (i) is made up of only A type of monomer, it is a homopolymer
Copolymer - If two types of monomeric units take part to form a polymeric structure, it is called as a copolymer.
Example = Nylon $6-6$, dacron, glyptal
Since (ii) is made up of $A$ and $B$ type of monomer, it is a copolymer.