The Samsung cable allows you to connect all your devices to an external monitor (TV, computer screen...). It can be used for AR/VR headset or your phone to an external monitor. The latter has a USB-C connector at one end and an HDMI connector at the other to transfer a video stream in 4k.
The HDMI cable allows to transfer the image, but also the sound. It is possible to connect your main monitor (a laptop for example) to a television during an AR or VR session, so that the people around you can enjoy it.