What is the difference between instr and substr functions

The Instr function returns the location of a substring in a string, while the substr function extract a substring from a string.

select instr('Learn pl sql functions', 'e') from dual;

would return 2


select substr('Software is ready', 10, 2) from dual;

would return 'is'

Syntax: Instr function and Substr function

Examples: Instr function and Substr function