When to use codeigniter where() function and when get_where() - codeigniter

Question

I've been reading docs regarding these 2 functions, but I still can't quite get the difference between these two.
I get it that get_where selects data from DB, but when should we use where() function and not get_where()?

Answer 1

get_where()
There are tons of other ways to get data using CodeIgniter’s ActiveRecord implementation, but you also have full SQL queries if you need them:
Example:
$query = $this->db->get_where('people', array('id' => 449587));
Ultimately, get_where() is the naive case, and certainly the most commonly-used in my code anyway — I can’t think of an another framework in any other language that enables you to be this productive with data with a single line of code.
get_where([$table = ''[, $where = NULL[, $limit = NULL[, $offset = NULL]]]])
Parameters:
$table (mixed) – The table(s) to fetch data from; string or array
$where (string) – The WHERE clause
$limit (int) – The LIMIT clause
$offset (int) – The OFFSET clause
This function is working as get() but with also allows the WHERE to be added directly.
Identical to the $this->db->get(); except that it permits you to add
a where clause in the second parameter, instead of using the
db->where() function.
where()
This function enables you to set WHERE clauses in your query.
You can also add where clauses, sort conditions and so forth:
$this->db->select('first_name', 'last_name');
$this->db->from('people');
$this->db->where('id', 449587);
$this->db->order_by('last_name, first_name');
$query = $this->db->get();
It’s possible to chain all these conditions together on a single line, but I prefer putting them on separate lines for readability.
In simple word, get_where is a luxury to use but where() gives you more flexibility to use.

Answer 2

The get_where is a combined function -so to speak- of the both where() and get() functions,
according to the documentation :
$this->db->get_where()
Identical to the above function except that it permits you to add a
"where" clause in the second parameter, instead of using the
db->where() function
also by take a quick look at the source code of the get_where() method you will notice that
if ($where !== NULL)
{
$this->where($where);
}
where $where is the second parameter of get_where() method.
In simple terms, $this->db->get_where('table name', 'where clause') is an alias for $this->db->where('where clause')->get('table name');