Recently the Rules have relaxed with regard to Sub-Domains and their use. They used to be the sole abused web creation for spammers and hackers, and thus were under such severe penalties that it simply made sense to abandon use of them.
Now, Sub-Domains are making an inroad with not only webmasters looking for a cognizant manner in which to expand existing website growth and still maintain some continuity and relevance that is so important to the Search Engine valuations, but also because domain names for Add-on's are becoming scarcer and scarcer with so many millions of people buying domains and driving up what used to be 2nd and 3rd tier names to prices that are now premium (if they are available at all!).
So, it does in fact make sense to create sub-domains that both have similar relevance to the Primary domains (i.e. Primary: JohnsToyStore.com Sub: ToyStoreCloseouts.JohnsToyStore.com or even Closeouts.JohnsToyStore.com), and if cleverly composed, Content on the Sub disimilar can make the entire Sub almost as valued as a Primary .... but it needs comply with all the Rules of website creation.
No matter how you dress it up, though, a Sub-Domain will always be considered "less" than an Add-On or Primary domain, insofar as it does not have it's own URL and specific tiered domain extension (.com; .org; etc.)
Now ... here are some more things that you were all asking for >>>> ... the differences between domain types...
Differences in Domain Types via URL Examples:
http://www.PrimaryDomain.com http://www.AddOnDomain.com which is an actual registered domain with Nameservers set at your VodaHost account
http://SubDomain.PrimaryDomain.com which is a fully functional non-registered domain created in your cPanel as an independent site (directory) in Main Account
... how to create the proper type of domain directory ... >> (Control Panel Tutorials, v.X3)
VodaHost operates both X and X3 versions of cPanel. Customers who joined after November 1, 2007 are on X3.
Adding an additional add-on domain name to your account
Creating a sub-domain ( A sub-domain is not an add-on) And ... how to PUBLISH ... >>
The method of publishing with Blue Voda to Add-On domains and Sub-Domains is virtually the same, by making simple changes within the Publish Dialog Box:
(Primary Account Domain)
public_html/ .........<--- leave blank
(Add-On Domain)
public_html/addondomain
(Sub-Domain, as shown on Primary)
public_html/primarydomainname/subdomainname
Publishing your web pages on the internet
...
as well as how to best link pages ... >>
* To link page-to-page in this new site -
if an add-on - the linking method is exactly the same as when using your Primary domain, as it has a unique domain from which to find the hosted site:
i.e.
http://www.AddOnDomain.com/next-page.html * To link page-to-page in a
subdomain, you will need to follow the same logical structure, only adding the variables as required:
i.e.
http://Sub-Domain.PrimaryDomain.com/next-page-title-here.html .
Linking your pages together (Hyperlinks with text, images etc...)