Scala 2 or 3 - What's the difference?

[oaf-0]

and which one should I choose?

[spamegg1]

If you are starting, go with the latest (3.5.1 currently).

There are lots and lots of differences, too many to explain here.

https://docs.scala-lang.org/scala3/new-in-scala3.html

[SethTisue]

see Scala FAQ | Scala Documentation