Perl

  • Perl has OOP capabilities, but it isn't what you'd call "Object-Oriented" considering it's principles & structure aren't oriented around the concept of OOP. Most case scenario, you won't be utilizing Perl's OOP features. Mainly because Perl's primary use is supplemental as it's a scripting language and by default it's procedural so OOP is completely optional.

Java

  • Java — much like C# — is actually oriented around the use of objects. Hence the term name. Virtually everything you do in Java will involve OOP; actually, there's little to nothing in Java that's not an object in some way, shape or form. Java and C# are also syntactically identical, so as such, if you have a firm grasp of the former or the latter, learning one or another would be easy as "Hello, world!" From my field of experience, I'm not very acquainted with either of these languages (more-so Java than Perl as I've written quite a few Perl applications before). But I understand the fundamental of these languages relatively well. Well enough to lecture you on the insides-and-outs, at the least.

In conclusion: Java is practically identical to C# whereas Perl is almost completely differs aside from practical procedural concepts common among a lot of other programming languages.

P.S. Excuse the mild tl;dr. I probably went just a bit overboard.

Good luck.