the Kiwanis club where I live is basically a service organization. they raise money to support local causes. I think anyone can join as long as they are sponsored by a current member. they have regular meetings and often have guest speakers - like the local School Superintendent will talk to them about some program that needs financial support.
the Shriners are a different story. as noted, they are an off-shoot of the Masons. There are Shriners' Children's hospitals in a number of cities. there is also a Shrine Circus that tours in the Midwest.
and the East-West Shrine Bowl is the longest-running College Football All-State Game. it's a fund-raiser for the Children's hospitals.
(I had a buddy who - whenever he would see a Shriners' unit in a parade - would always yell "Drink Up, Shriners" at them. so that's what I think of when I see or hear anything about the Shriners. I've seen Shriners groups appear in parades with motorcycle units.)