Really confused about swarm

Hello, everyone reading this.

I’ve been using Swarm for while now to run some services of my own use.

Currently using docker 17.03.1 and start Swarm docker swarm init --advertise-addr <ip> --listen-addr <ip> on the manager host and then docker swarm join --token=XXX ---advertise-addr <ip> --listen-addr <ip> <manager ip> on each worker host.

Thing is I’ve recently found there are Docker Swarm images as well and you can pull these and run them on your host, so no need to do the first steps i do on every host? how do these images work? how do they differ from the “conventional” way i start a swarm? how can they connect with each other? is each image treated as a different host? that means if i run 2 swarm images on one host they are treated as different hosts? do the services run on top/inside of these swarm images?

Sorry for so many questions, but i’m a bit lost/confused.

One last question, is there any documentacion on how to work with these images?

thanks for your time.