There is a whole new language - but you can learn it a little at a time as you go along. This page sets out to explain some of the things that are fundamentally different, so that you are immediately more comfortable.
There is no equivalent in the Windows world. The basis of any distribution is the linux kernel, which is frequently updated, but is the same for everyone. On top of that there are other layers which can affect how your desktop looks. Most people do not want to have to make all those decisions - and it takes a lot of technical skill to set up a desktop doing it all yourself- so distributions are made. Think of it in terms of brand names. You may have Mageia, Fedora, Debian, KUbuntu or one of many others. All will offer you the same applications - you will be able to follow tutorials in any of them - but they will have their own look and feel, and sometimes there are minor differences.
If you find that the instructions don't work for you, visit the forum and ask. Someone will help you with the differences.
If you feel more comfortable asking questions by chatting, How to chat with other KDE users will help you set up and get chatting