Posted 25 August 2012 - 12:47 PM
a library is a set of code or module imported into your program. So somepoint you have a statement in your code saying something like "using slick.somethingorother" or "import slick" or something like that. Libraries can contain anything, routines for graphics, maths, sounds, databases, compression algorithms whatever. Even printing to the command line will use some sort of library.
More specifically a grapihcs library is just that, a library providing routines to draw graphics. These might be either a GUI (think a traditional window on your computer with some text boxes and buttons etc) or raw 2d or 3d graphics useful in games. One for GUI's might be referred to as a GUI library instead, swing and AWT are 2 java ones I think (I don't know java).
An engine will be a collection of libraries (or 1 library with features of many libraries instead), these will usually include 2d and 3d graphics, sound, networking and input libraries etc.
Games will only look like the content you provide. Basically a game will look the same no matter whether its made in andEngine, libGDX or slick assuming you give it the same images and sound to render/play.
Some of the engines may offer different post processing effects (like an effect called bloom that is sometimes used in 3d games) but on a card game I don't think you'll be using those so much.