difference between composer update and composer dump-autoload in laravel

Question

sometime to update composer file.I use two different command composer update and composer dump-autoload .

And both those have different result in command prompt like:

C:\xampp\htdocs\rabble>composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Nothing to install or update
Generating autoload files
Generating optimized class loader

And:

C:\xampp\htdocs\rabble>composer dump-autoload
Generating autoload files

Answer 1

composer update always regenerates composer.lock and installs the lastest versions of available packages based on composer.json

composer dump-autoload won't download a thing. It just regenerates the list of all classes that need to be included in the project (autoload_classmap.php). Ideal for when you have a new class inside your project