For most parts, Perl is very much like PHP. You can easily make 90% of most PHP code work in Perl with only trivial changes, such as splitting up PHP's arrays into Perl's arrays and hashes. Note that an array in PHP is like a Perl's array- and hash-refs, not plain arrays/hashes. And you'll have to translate those built-in keywords in PHP without any equivalent in Perl, into calls into modules.

OO is one area where Perl and PHP are quite different. For a very gentle intro to Perl OOP, check out perlboot.