Can someone build a website from wordpress.com as well as wordpress.org If you can will the website be ranked as well by the search engines as blogger.com or another blogging / website would be.

http://en.support.wordpress.com/com-vs-org/

Can someone build a website from wordpress.com as well as wordpress.org

WordPress.com is a hosting service that uses the software you can download from WordPress.org. I guess the answer is no, but it's hard to say because they are two completely different things.

You can have a blog hosted on WordPress.com or you can self-host your own blog using a copy of WordPress downloaded from WordPress.org.

If you can will the website be ranked as well by the search engines as blogger.com or another blogging / website would be

Search engines shouldn't really be a factor in deciding between a WordPress.com blog and installing a copy of WordPress on your own site; as far as I know search engines don't care. You can have your own domain mapped to your WordPress.com blog so even if search engines did care, they wouldn't know the difference.

Wordpress.com uses Wordpress MU (Multi User) and the MU model has now been incorporated into WP3, on installation you can choose to set it up in single blog mode or in multiple blog mode.

Though to use multiple blog mode you do need to be able to setup wildcard DNS so that anything.domain.tld and everything.domain.tld will resolve to the same server , the MU module and .htaccess sort out which "blog" will serve out the content.

And NO search engines really don't "care"

wordpress and blogger also provide the facility of providing domain. You can register with both wordpress.com as well as wordpress.org. But have to follow some rules. Read there guidelines carefully you will get all the information.

yes it is,but you should follow in their rules..good luck to you