Groovy had a very different initial design philosophy compared to Kotlin. The Groovy design philosophy was give Java developers a good highly-dynamic scripting language that still felt like Java but also made it more suitable for writing quick and dirty plugins, scripts and other extension bits to Java programs.

Kotlin is more in the "Java is great already, but has a lot of legacy issues, let's take all the stuff learned in the last two decades and make a Java++"

`a == b` compiles to `a.equals(b)`, if you want reference equality you need to type `a === b`.