AdWord Express Campaigns have become Smart Campaigns, as stated in Google Ads Help.
It’s also said that not only do Smart Ads have all the benefits of AdWord Express, but also include a number of extended functionalities.
Among the features of Smart Campaigns, you can find quick ad creation and publishing, pay-per-click, generating website traffic, minimal time and effort thanks to automation, etc.
AdWords Express is a simplified advertising platform for small businesses. It used to take about 15 minutes to launch a campaign there, according to Google.