php: different between array( ) and { } -

what's different between

array     (         [user_id] => 1         [username] => user         [first_name] => hello         [last_name] => world     ) 

and

{     user_id: "1",     username:"user",     first_name:"hello",     last_name:"world" } 

? , how convert them in php?

edit: add details

actually i'm using redis zunionstore , zrevrange combine user data. result returns me :

array (     [0] =>{"user_id":"1","username":"user","first_name:hello","last_name:world"}     [1] => ... ) 

since have process data, want this:

array (     [0] => array         (             [user_id] => 1             [username] => user             [first_name] => hello             [last_name] => world         )  ... ) 

so there easy way convert instead of using loop json_decode each element? thx

the first string output of print_r function. example:

$array=array('key'=>'value'); print_r($array); 

outputs:

array (     [key] => value ) 

your second json-like, alto lacks of double-quotes keys.
can't convert them directly.

you convert json php array json_decode if second string this:

{     "user_id": "1",     "username":"user"     ... }