system/Validation/Rules.php
public function differs(string $str = null, string $field, array $data): bool
	{
		return array_key_exists($field, $data) ? ($str !== $data[$field]) : false;
	}
public function differs(string $str = null, string $field, array $data): bool
	{
		return array_key_exists($field, $data) ? ($str !== $data[$field]) : false;
	}
The value does not match another field in $data.

@param string $str
@param string $field
@param array  $data  Other field/value pairs

@return boolean