Golang is focused on scaling/concurrency, is very compact and fairly quick to learn. You can compile a single binary and deploy it anywhere. You can build a web server in a few lines of code. It's really strong for processing tons of requests, web API's and backend code.

Java requires a whole app server which is more of a pain to setup. (generally speaking for web dev, think Tomcat, JBoss). It's way more verbose and you really need to rely on the power of an IDE to help code for you, importing class libraries, etc.

Spend a few hours with each, they're very different. Coming from Node/PHP you should be able to pickup Golang faster.