Hi @becfl,
A warm welcome to the Bunnings Workshop community and thank you for your question.
I am 99% sure based on the second image that it is composite as this is not what natural timber looks like. You can confirm this by looking at the end of a board. If it is timber, there will be visible growth rings, if it is composite there won't.
Check out the Ekodeck Decking Care & Maintenance Guide.
Ekodeck, which is our main composite decking supplier, recommends using hot soapy water and a deck scrub brush to scrub the deck, before washing it of with a pressure cleaner with a fan nozzle attachment.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
