WP Easy Events is an event management and registration system. WooCommerce WordPress plugin is an ecommerce system which can handle ticketing for WP Easy Events. WP Easy Events WooCommerce Extension allows you to use WooCommerce along with WP Easy Events.
In other words, if you'd like to use WooCommerce for ticketing, you must have WooCommerce Extension to make it work. Easy Digital Downloads WordPress plugin is an alternative ecommerce system which can be used for ticketing as well.