Few problems fall solely into one design discipline’s skillset. The lines between them are blurry. For example, even a basic user interface problem has elements of communication design and experience design. Most designers are comfortable in more than just one area. Just like medical doctors, designers tend to go through some common training (like visual thinking for example), then they hone their skills further and specialise in certain areas over others.
Since you have selected Interactions & Experiences, here is some further information on the design skillsets that may be needed in this category.
Service design involves the activity of planning and organizing people, infrastructure, communications, and material components of a service in order to improve its quality and the interaction between providers and customers. Service design emerged out of the private sector with a strong focus on service industries such as hospitality and health. Service design gained widespread adoption in the UK, for example, where it was applied to make the delivery of the national healthcare more user friendly at each touchpoint.
User experience design (UX, UXD, UED or XD) design is the practice of designing products, processes, services, events, and environments with a focus on the quality of the user's experience, particularly the level of engagement and satisfaction that the user derives from a product or service while it addresses their needs and context. User Experience design can help provide global health practitioners with a holistic picture of user needs across a range of different touchpoints. It is an approach that helps reveal key gaps in quality service delivery that might otherwise fall through the cracks between different actors within the health system.
Web or digital design encompasses many different skills and disciplines in the production and maintenance of websites. The different areas of web design include web graphic design; user interface design (UI design); authoring, including standardised code and proprietary software; user experience design (UX design); and search engine optimization. Often many individuals will work in teams covering different aspects of the design process, although some designers will cover them all.