Below is explained the differences between PCL5, PCL5e, PCL6, and PS (Post Script) printer drivers. Please try and use PCL5 or PCL5e first unless instructed otherwise.
PCL5/PCL5e (the latter being an extended version) is an escape-based language, using an ASCII representation, but is relatively unstructured (although quite powerful); so you can edit a PCL5 print stream relatively easily. PCL5 and PCL5e are less restrictive and more accepted across multiple windows platforms.
PCL6 (aka PCL XL) is a completely different language, uses a binary representation, and is much more structured; for these reasons, it is much more difficult to edit a PCL6 print stream. PCL XL has a closer relationship to the GDI used within Windows than does PCL5; most PCL6 drivers now offer more features than their PCL5 equivalents. However, PCL6 is not compatible with every version of Windows including the differences between 32bit and 64bit versions.
PostScript (PS) is a computer language for creating vector graphics. It is a dynamically typed, concatenative programming language. Simply put, it prints large format jobs as well as rich text. Generally not used for standard sized documents.
So by general rule you should install PCL5 or PCL5e first unless there is a specific need for PCL6 or PS (Post Script). Example: Post Script should be used when dealing with a large printer (paper size 18 inches at its smallest side or larger) including plotter printers.
TWAIN Drivers are specific to scanning only.
TWAIN is a widely-used program that lets you scan an image (using a scanner ) directly into the application (such as PhotoShop) where you want to work with the image. Without TWAIN, you would have to close an application that was open, open a special application to receive the image, and then move the image to the application where you wanted to work with it. The TWAIN driver runs between an application and the scanner hardware. TWAIN usually comes as part of the software package you get when you buy a scanner. It’s also integrated into PhotoShop and similar image manipulation programs.