A "content type" is what I like to use. It can be the basic types that
exist today in core (a page, a blog entry), or types that are created
by specialized modules (e.g. an image, an event), or what site owners
create using CCK.
A "content item" is an instance of content type (for the OO heads among us).
Content item should be a better name for what we call "node" today.
Post can also be used, but not every item is posted to the site. For example
aggregator and friends create items from other sites.
