If you install SQL Server Express Edition, it will install only Database Engine Services.
In configuration manager it shows SQL Server and SQL Server Agent services, but SQL Server agent in disable state. Why it installed SQL Server Agent is because if you perform upgrade from Express Edition to any other edition it enables the service after validating the installation and also no need to replace all files at the time of upgrade, because of that it installs SQL Server Agent service along with Express Edition.
Express Edition comes in different versions.
Express Edition with SSMS
Database Engine, Import and Export Data (No SSMS)
Express Edition with Advanced Features
Database Engine, SSMS, Reporting Services Configuration Manager, BIDS, Import and Export Data.