Over the last 15 years, I've seen a lot of interesting ways an organizational structure will influence a project. I've worked in projectized, functional, matrixed, and even composite environments. These terms of management are interesting to me because I had to understand the definitions as part of the PMP exam. At my last engagement, ironically, my boss went so far as to use Wikipedia to get the definition for Matrix Management without realizing I was one of the contributing authors to the page. Personally, I would prefer to use the PMBOK. I've noticed quite a few people have modified the Matrix definition on Wikipedia.
Today I was reading the PMBOK (I'm strange like that) reviewing differences between the 3rd and 4th editions. What I noticed were definitions (in the glossary) for each organization structure with the exception of composite. Composite, by the way, is new to the 4th edition. Perhaps PMI will take notice and add it at a later date. Below you'll find figures and definitions of each.