S2S
VPN
VPN connection: A secure connection between your on-premises equipment and your VPCs. VPN tunnel: An encrypted link where data can pass from the customer network to or from AWS. Each VPN connection includes two VPN tunnels which you can simultaneously use for high availability.
The vpn tunnel, is what that is based on IPSec, VPN connection refers to the abstract concept of two vpn tunnels enabling VPN connection
Customer Gateway
Customer gateway: An AWS resource which provides information to AWS about your customer gateway device. Customer gateway device: A physical device or software application on your side of the Site-to-Site VPN connection.
You probably setup a device on on-premises, and you create a AWS resource customer gateway, which lets AWS know the device
VPN Endpoints
Target gateway: A generic term for the VPN endpoint on the Amazon side of the Site-to-Site VPN connection. Virtual private gateway: A virtual private gateway is the VPN endpoint on the Amazon side of your Site-to-Site VPN connection that can be attached to a single VPC. Transit gateway: A transit hub that can be used to interconnect multiple VPCs and on-premises networks, and as a VPN endpoint for the Amazon side of the Site-to-Site VPN connection.
VPN endpoint or Target gateway, in AWS is either VPW or TGW