What is the difference between fseek and lseek?

Answer 1

lseek is a system call, but fseek is a C function belonging to the ANSI C standard library, and included in the file stdio.h

lseek uses file descriptor (return by open system call), but fseek uses pointer to FILE structure (return by fopen ANSI C library function) (though file desctor and FILE * can be used interchangeably several times).

System calls are to communicate directly with an operating system. Generally, system calls are slower than normal function calls.