What are the main differences between OpenVPN open source and OpenVPN Access Server?

Features OpenVPN open source OpenVPN Access Server
TLS encrypted VPN tunnels
Graphical web interface
Automated certificate creation
Pre-configured client software
Easy deployment
Pre-built virtual appliances
Simple user management
High-availability failover solution
Multi-node cluster solution
Easy scalability
Configurable encryption ciphers
LDAP support included
RADIUS support included
Multi-daemon mode