Today's mobile devices are multi-functional devices capable of hosting a broad range of applications for both business and consumer use. The increasing importance of Smartphone has triggered intense competition among technology like Symbian, Google, Microsoft and Apple. This paper presents a brief review and comparison of the Android operating system from Google and iPhone operating system from Apple. The comparison is done on the basis of their platform, their performances and the growth in mobile land. The salient new key features introduced in Android and IOS are also described.