they use same language as they did in real life, but in animation mostly what they did (the story anime itself) are opposite to real japanese.

One difference is the tone (or pitch) of the voice. Not all the animation but most of them have distinctive tones from Japanese spoken everyday. If it's for girls' voice, generally the pitch is higher and sounds like a bit child even though the character is not a child. They are called "アニメ声" or "萌え声", some people naturally have that kind of voice and often people comment on that, like "Oh, you have an アニメ声." or "Your voice is アニメ声" something like that. For men's voice, it's called "イケボ" if I'm not mistaken. I don't know how to describe the voice but I know it is different from how men speak normally. You can google them and check these voice out as many people try to speak in those voice or teach how to do it to other people. It can be a great party trick :)