Single mode and multi mode are two different types of operation modes. Single mode is a mode of operation in which only one user can access a system at a time. Multi mode, on the other hand, allows multiple users to access the system simultaneously. Single mode is often used for applications that require a high level of security, while multi mode is used for applications that require multiple users to collaborate. Both modes have their advantages and disadvantages, and the choice of which mode to use depends on the specific application.