Virtualization is indeed a key element of cloud computing because virtualization is related to software manipulation with hardware. Whereas cloud computing is on-demand delivery of that virtualized shared computing resources, software and/or data as a service. Two technologies in many cases are offered together with a great level of flexibility and security. Based on these premises, private sector companies would adopt virtualization on cloud computing at their business paces whereby public sector organizations may reluctant to adopt virtualization and cloud computing due to risk averse nature, etc. Within these contexts, success and failure cases of virtualization and cloud computing in private sector and public sector in Korea are benchmarked. Furthermore, identifying similarity and differences of key success factors and lessons learned from two sectors and highlighting future avenues of virtualization in cloud paradigm are suggested, wherein.