Answer Posted / eng abedalmohdi almomani

system call can be called from either kernel space or user
space(in this case include switch to privilage mode) and
executed in kernel space while library called only from
user programm and may call systemcall to perform it is
function like "printf" that need "write" system call while
other not need kernel at all like sin(),cos().....

systemcall examples : write,read,close,mmap,open,.......
library examples: fopen,fclose,printf,scanf,fscanf,.....

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