ICT Capabilities and the Digital Technologies learning area have strong relevant connections but the key difference is essentially: 

• ICT capabilities: being able to use ICTs effectively and know which ICTs to select for specific tasks. It also involves learning about safe use and practice.
  
• Digital Technologies: Understanding how those ICTs actually work, learning a literacy in coding which underpins being able to create technology and learning about digital systems: hardware and software. It also emphasises a way of thinking that is important to creating solutions (like certain skills and processes we develop in mathematics and literacy).

The difference between "using ICT" and "creating ICT" is like the difference between using a game and being able to create a game. It is the difference between using an Instagram filter and being able to create your own photo filters. Learning how to create involves having an appreciation and understanding of how the technology and applications we use work. It's the "science" of technology.