Publishing and communication are similar activities in that they both involve making material available to the public. Under Australian law, they are two separate rights that belong to the copyright owner.
You publish your work when you or another authorised person such as your publisher supply reproductions of the work to the public and the work has not been made publicly available before. You communicate your work to the public when you or another authorised person make it available online or electronically transmit it to the public.
An act of communication to the public can also be an act of publication. If you make your work available online, and it has not previously been made available to the public, you are arguably “publishing” it in terms of the Copyright Act. This is because you are supplying reproductions to the public - the public can download a reproduction to view, save or print.
When you publish or communicate your work, you need to protect your own copyright and respect the copyright of others. If you act as a publisher, you need to respect the rights of your authors while at the same time ensuring the viability of your publication.