In computing, an emulator is hardware or software that enables one computer system (called the host) to behave like another computer system (called the guest). An emulator typically enables the host system to run software or use peripheral devices designed for the guest system.
i.e. and e.g. are abbreviations of Latin phrases and each has its own specific meaning. i.e. stands for id est, meaning that is.. It is used to explain what exactly something means, or to say the same thing in other words. It is an abbreviation (Latin) of id est. Meaning that is.
As far as I know ( my personal belief) , there is no difference between the two terms.. MRI stands for Magnetic Resonance Imaging and so does MR Screening. Its just a procedure using MRI as a technique to screen the person. It is a good diagnostic tool to analyse whats been happening in the L4 / L5 etc since it takes fine slices of the desired organ/body part and gives a clear picture of whats happening inside it.