The difference between transcription and translation lies in their roles in protein synthesis. Transcription is the process where a segment of DNA is copied into messenger RNA (mRNA) by the enzyme RNA polymerase. This occurs in the nucleus and results in the formation of mRNA that carries the genetic instructions to the ribosome. In contrast, translation is the process that occurs in the cytoplasm, wherein the ribosome reads the mRNA sequence and assembles the corresponding amino acids into a polypeptide chain, forming a protein. Both processes are essential for gene expression.