Subdomain and Subdirectory - What's The Difference?

[Terrence Taitt]

Can sometime please tell me the difference between subdirectory and subdomain? I am struggling to comprehend the difference (or similarity) between the the two. For example:

sports.examplesite.com and http://www.examplesite.com/base-ball-games

[paulgl]

A subdirectory is just another sub topic of your main site, all related.

A subdomain is for an entirely different website than your main one.
It is treated as a different domain and different website.

It is useful for forum.domain.com, email.domain.com, otherprogram.domain.com.
or similar.

It's not really for just different, but related pages of your main domain.

It used in all cases, however, like the go.com and about.com network.
Wikipedia is one example of not using it for each thing. Digitalpoint
uses forum.digitalpoint.com probably as the forum is unrelated
to their services.

For normal wesbites like mine, and I assume yours, subdomains are not
needed and really take on an SEO life of their own.

Paul