cDNA is complementary DNA, only having single template of original DNA and another of cloned RNA template, but genomic DNA has basic structure that contains one conserved helix and another synthesized by the Okazaki fragments, it has linear well arranged sequences naturally placed, but in cDNA genes and sequences of your choice are alleviated for incorporation through any process of insertion.
DNA and cDNA are kinds of nucleic acids; both are made up of nucleotides. Even though, they are structurally similar, their function and the way of synthesis differs from each other.
DNA is a nucleic acid that contains the genetic instructions used in all eukaryotes and some prokaryotes. It is the main constituent of the chromosomes and carries the genetic information in the cell from parents to offspring
cDNA stands for Complementary DNA. This is a form of DNA artificially synthesized by a given mature messenger RNA (mRNA), which serves as a template in the presence of reverse transcriptase enzyme. In most eukaryotes, expressed segments of the gene are called exons; exons are separated by introns (intervening sequences), which are not coding sequences.