Domain Registration
You need a Domain Name (i.e. yourbusinessname.com). The domain Name is registered and in the same way as leasing or renting a house/shop which has an address. You never 'own' it.
Web & Email Hosting
You need a Web Host. This is the inside of your house/shop. This too is leased or rented and this is where your website will be. This is where the people visit after you set it up and optimize it for your business.
Web Hosting needs mail and email accounts have to be configured for delivery.
