What is the difference between php.ini and .htaccess?

Question

Assume if I want to change the value of

php_value post_max_size 20M in .htaccess

post_max_size 20M in php.ini

Both will do same operation. So

Answer 1

Configuration values put in PHP.ini is for the entire server, it gets applied to all the sites running on that server. Where as configuration values put in .htaccess is for individual sites.