There are basically four ways that fonts appear in your applications: the operating system's Fonts folder, a type manager, local application folders, or the printer driver.
This item doesn't need a lot of explanation. Well, maybe this: If you wonder why fonts with file extensions of FON don't appear in some applications, it's because those applications have been instructed not to (meaning that some apps will let you use them, some won't). Word, for instance, cannot use FON-type fonts. Notepad can.
These applications, such as Adobe Type Manager, allow you to turn on fonts that are in locations other than the system's Fonts folder.
Some applications (Illustrator, for example), can use a local fonts folder, which is simply a folder tucked away inside the main Illustrator folder. If the application folder is the only location of the fonts and they are not enabled through a type manager, fonts installed to this folder won't be seen by other programs.
If you have fonts in a local folder, you can move them into your main font library and delete them from the local folder, thereby making them available to all your applications and not using any additional disk space.
When you install a printer, the printer driver provides some feedback to the operating system, identifying the fonts that it believes are resident within the printer. These fonts may or may not be installed on your computer, which can lead to numerous problems.
Windows, thinking that it's doing you a favor, lets you use these resident fonts in applications even if they are not actually installed on your computer. That's why when a PostScript printer is your default printer, you can use Times, but when you switch to a non-PostScript printer, it disappears. If the real Times font is installed and enabled via the operating system or via a type manager, it will be available throughout all applications and available no matter which printer your are attached to.