With the Basic plan you can manage one site with an unlimited number of domains. With the Professional plan you can manage up to 5 sites and the Enterprise plan allows you to manage an unlimited amount of sites with one account!
You can manage multiple domains for your site in one spot. Canonicalize your urls, set the local, and choose what site each domain should represent... These are just some of the many options provided for your domains.
With the Style Classes feature you can manage the styles for all of your sites in one spot. By doing this, you can ensure consistent branding for each site that you create!
If you choose to have multiple accounts for your different sites, you can go and access each respective site easily from your menu. You can also import the site's skeleton into your other sites alowing you to build and develop multiple sites quickly and with ease.