The Computer User:
This is a person that feels no emotional ties to FOSS/Linux. The computer is only tool to get the job done and they use Linux because they need the tool which can be found in linux for the job they are trying to accomplish. This type of user may have no idea of what FOSS or Linux is. They glad to just know that their computer works when they need it.
The Dual Booter:
This is the person who typically has some computer savvy about them. Some of them are person who decided to give Linux a try because of an interesting article about a new Linux distro or because they know a Linux geek who recommended it. They might make a forum post or two to try and solve an issue they are having, but odds are if the distro doesn't "just work" they will start going on about how Linux "isn't ready for the average user" or "will never make it as a desktop operating system".
This type of person is someone who uses Linux because they feel it is a superior, secure, or more stable operating environment. Typically this is someone who knows about the computer a bit and isn't afraid to post on a forum asking a question or get their system up and running. They are typically willing to use restricted codecs and closed source video drivers to get the performance and functionality they need out of their system. While it is not uncommon for them to recommend Linux to their family and friends, most times they will even help them get it setup, they realize that some people are happy with Windows and they acknowledge this.
This type is someone who they use Linux not only because it is fast, secure, and stable, but because it is FOSS. Usually they know the ins and outs of their system. If their hardware does not work right "out of the box" on their favorite distro they are willing to spend hours pouring over manuals and help pages to get it working. They almost constantly preach about the evils of Windows and Apple and take every chance they get to convert those they know to Linux or and FOSS operating system.