How does dip treatment differ from pressure treatment? The clue is in the name, and it really is as simple as it sounds. During manufacturing, the wood is dipped into a vat of preservatives. This wood stain provides base level coverage i.e. the preservatives don't go deep into the wood as you'd expect with pressure treatment. This protects the exposed areas of wood, and provides initial protection against rot and mould.
You can tell dip treated wood through the colouring; honey brown and dark brown are good indicators of dip treated wood. Whereas pressure treated timber has a more natural look with a blue/green tinge.
You will need to maintain dip treated goods though, as eventually the protective layer will wear away. This can be done by painting or spraying the wood with wood preservative once the colour fades, or face the risk of rot.