types of users

Can someone explain me the relevance, usage & control of all the various types of users, namely: subscriber, contributor, author, editor & administrator.
Though i read the roles & capabilities section in the online wp tutorial, but could not understand its true usage at the front hand.

my website is https://www.medinmark.com & i wish the audience to register under distinct user categories, with different roles & capabilities.

But i am experiencing difficulty in comprehending properly, how to manage this feature.

Kindly someone guide me please.