PHP vs Javascript

What are the similarities and differences between these two languages?

What i've gathered so far

They're both web based scripting languages.
PHP is an open source alternative to Microsoft's. It is a recursive acronym for PhpHypertextProcessing.

What i'd like to know is what can you do in JS but not in PHP and vice versa. Also, could Anusymous be written in JS ?

>>1
PHP was originally a set of tools written by someone that he called Personal Home Page