Python3.x vs Python2.x

Question

What are the differences? Why do they have two? My school teaches 2.x but solo learn teaches 3.x. Why cant we all learn the same.

Answer 1

2.x was the only and main version for a long time. developers learned it very good, created a lot of libraries and got used to all of this.
then 3.x was released, it was not totally compatible with 2.x, there wasn't much libraries for it, so nobody wanted to risk the stability.
years after, 3.x provides almost full list of modules, libraries and possibilities of 2.x and even more, can easily be compatible with 2.x and is the main supported version of Python (but 2.x is still supported too because of great amount of programs written in it).
but still great part of developers stay on 2.x just because of habit and because they support software written before on 2.x and it would be harder to rewrite everything on 3.x

Answer 2

Most Linux distributions use Python 2 as the system Python, although you can also install Python 3 alongside 2. Arch Linux is one of the few Linux distributions that uses Python 3 as the system python.

If you are learning Python, learn Python 3. Python 2 will be supported by the Python Software Foundation till 2020.