Rosies differentiates between 'homelessness' and 'houselessness'. We tend to think of homelessness in terms of shelter - this is a physical state, and one that Rosies refers to as 'houselessness'. A physical structure is missing.
Homelessness, on the other hand, is primarily an emotional condition. It's the absence of social, family, and community networks that most of us take for granted. Homelessness is intangible - it often coexists with houselessness, but not necessarily. Just as there are people without physical shelter who consider that they have a 'home' with family, friends, and support networks, there are also people who have regular shelter who don't feel they have a home.
Fr Pat MacAnally OMI, a former chaplain to Rosies, explains the difference between houselessness and homelessness here.