Gene cloning or DNA cloning or Molecular cloning is a process of making a multiple, identical copies of gene or specific DNA fragment. In order to achieve replication of cloned genes, a cloning vectors are used which are self-replicating inside the host cell due to presence of origin of replication. These cells with cloned genes are then preserved for future use. There are many cloning vectors like plasmids, phages, cosmids etc.
An expression vectors also called as an expression constructs are generally used to introduce a specific gene into a target cell. Once the expression vector gets introduced inside the target cell, then it (vector) starts producing or expressing the protein product that is encoded by the gene it carries. Vector use transcription and translation machinery of target cell. An expression vectors are used to produce many recombinant protein. One such example is of insulin where expression vector carry genes for insulin production in the Escherichia coli.