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

Apache is the HTTP server. It is configured with a .htaccess file placed in the root of the website/Application means every application has its own .htaccess file.

php.ini is the fastest way to affect PHP's functionality.