yes and no. each distribution of linux varies a couple of things, but many things stay the same. every distribution has a linux kernel. most have the latest stable one. I think it is 2.4.24. Some have older and some have the bleeding edge ones (2.6.x or 2.5.x). most distribution that you will use wil have the xsystem, desktop managers, and window managers. these are not centric to any real distribution, but some have modded theirs a little to make it work better. The real difference comes in options, ease of install and maintence, speed, and stability. Some distributions like mandrake and fedora are very easy to install and maintain, but they are often slower and sometimes less stable because of what they do to keep the install and method of maintenence easy. these two have a graphical install interface, and guide you through the install. they also are quick to install compared to other distributions. They startup in the gui after installatioin, and most all maintence can be done through the gui. however because of the quick install many options that would speed up the use of it are left out because many of them deal with your hardware. you can get these type of Distributions to run fast, but it is harder in my opinion than others. Gentoo is the exact opposite. It is very hard to install, but you have complete control over the install. the cd gives you all the stuff, you just have to configure, compile and install it all. since you can configure the install gentoo will be custom built for your system and all the mishmash that you don't need is left out (while in mandrake and fedora and others like this leave most of this there). In slackware (what I use) its pretty easy to install, but it doesn't really complete the install. you still have to set up vaarious little things to get it to run optimally. while doesn't install custom to your system, it is very easy to set up if you know what you are doing. Slackware and gentoo are known to be very stable. Gentoo is known to be fast, and slackware can be just as fast with a little work. Another difference between distributions is the way to get programs. some like fedora, red hat, and mandrake, use rpms primarily. there is a program that will install these and put the program on your computer. gentoo uses portages. these include links to dependencies (usually libraries of files like those for python, freetype, etc). if you don't have the dependency it will install it also. this is a very good system because the "dependency hell" that you run into with the rpm distros can become very frustrating. Slackware uses a package system. its like the rpms, but you can remove packages later on with no harm done to your computer very easily. with almost all distros (if it has the development pack install it many don't and the development pack is automatically included(you really ought to do this) ) you can complile and install the source of many programs. sometimes this is easy sometimes its not, but often its the only way. The last difference is support from the vendor. some distribution have very good support from the vendor, while others don't. often though, you can find help at various linux forums if you have problems.
Think of Distributions as different forms of the same type of program. they all will do the same thing, some are easier to use, some are quicker, some look better, and some have better support. I suggest you start with the easiest and learn it then move on to different distributions if you feel the need.
