I started to learn Kotlin today and am already confused:
Is there any difference between between Ant, Maven and Gradle?

AFAIK kotlin is a general purpose language used like a scripting language for Java (e.g. the dynamic typing)
Ant is a general tool for automating tasks like file manipulation which was mainly used to prepare and build Java archives. Maven served the same purpose but was more build specific (mainly dependency management) and has overtaken the position of ant.
Gradle does the same like maven but combined with a general purpose language called groovy.

So I think the better question would be, what's the difference between kotlin and groovy? Which I don't know ;D

OMG. kotlin is an extention of Java, that adds sone new features. The best part is the small size, and generated class file bytecode compatibilty with current JVM. asking what is the difference between Maven, ant, and gradle... well, you can google that. but in short, ant is an xml based build system for java projects. gradle is code based build system, and Maven is an abstract build system, that can do all kind of interesting things.