Kernel mode
In this Kernel mode, running the code has total and unrestricted access to each underlying hardware and can execute any CPU instruction and reference any memory address. Kernel mode is usually reserved for the lowest-level, most advanced functions of the operating system. Crashing the kernel-mode is catastrophic; they will halt the entire PC.
User Mode
In User Mode, the run the code cannot directly access hardware or reference memory. Code that runs in the user mode should delegate to the system APIs to access the hardware or memory. Due to which protection afforded by a isolation, crashes in your user mode are always recoverable. Almost all the code running on the computer will be executed in user mode.
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