The 4G technology is already introduced in 2010 where the user can access the internet at anywhere and anytime. Here Mobile Broad Band (MBB) is the only application scenario. 5G technology had been launched in the year 2020. In comparison to 4G, 5G is far advanced. When 4G is updated to 5G, there will be increase in wireless communication system in an exponential manner. It has three application scenarios i.e eMBB, URLLC and mMTC. Among them, URLLC is the most critical condition. In URLLC, two terms are increase in Reliability and reduction of Latency and their interrelation. URLLC will be used in vehicles, factories etc to improve the smartness. During the reign of 5G, several techniques such as TSN, D2D, CoMP, MEC, Mobile Caching etc. are used for the reduction of latency and increase in reliability. 5G will not able to fulfill the all the user demand such as sense of touch. 6G is another new technology updated from 5G and it will be launched around 2030. The application scenarios present in 6G will be enhanced in comparison to 5G. Here the URLLC will convert into enhanced URLLC. The reasons for the decrease in latency and improvement of reliability such as Artificial Intelligence, TeraHertz Communication, 3D networking, Tactile Internet, Full automation etc. This article presents the review of reliability and latency both in 5G and 6G. This article describes the features of reliability and latency for both 5G and 6G, their comparison, reasons and factors regarding the increase in reliability and reduction of latency. It will be helpful for the researchers to carry out some research works in critical conditions in future.

URLLC; eMBB; mMTC; massive MIMO; 3GPP; SON; AI; UAV; feMBB; eURLLC; uMUB; uHSLLC; uHDD