WooCommerce installs some custom tables to store its data during install. More about tables installed: https://github.com/woocommerce/woocommerce/wiki/Database-Description
Tables are removed when uninstalling WooCommerce only, not during deactivation.
Note: When defining a WordPress SQL table prefix, make sure it’s less than 20 characters. Otherwise WooCommerce is unable to create all tables properly. This could lead to the following issue.