"Affordable" is a subjective, relative term that can be applied to any level of income. For our purposes NeahCasa resonates with the definition used by the City of Bend:
"Affordable" housing refers to housing that requires the residents to spend no more than 30% of their household incomes on housing related expenses. For homebuyers, housing related expenses include mortgage principle and interest, taxes, property insurance, mortgage insurance and essential utilities. For renters, housing related expenses include rent and essential utilities. Qualifying projects are those that received federal or state affordable housing funding and/or those that contain projects that are affordable to households earning at or below 100% of Area Median Income."
According to the New Hampshire Workforce Housing Council (www.workforcehousingnh.com): "Workforce Housing" means a broad range of owner and renter housing, meeting the needs of families and individuals whose income is generally below 120% of the area median. Workforce Housing can include, but is not limited to, subsidized and affordable housing. It is best provided near places of employment."
From Wikipedia: "Workforce Housing is a relatively new term that is increasingly popular among planners, government administrators and housing activists, and is gaining cachet with home builders, developers and lenders. "Workforce housing" can refer to almost any housing, but always refers to "affordable housing".... Most appropriately, "workforce housing" connotes housing intended to appeal to key members of the workforce such as police officers, teachers, nurses and medical technicians, office workers, etc., whom we think of as "the backbone of any successful community" (Lisa Arthur, Miami Herald, June 6, 2006)....."Workforce housing," then, implies a subjective change in awareness of a widespread social condition that has been referred to generally by terms such as "affordable housing."
Public Housing (or Social Housing) is housing owned directly by a government agency.
Subsidized Housing is housing in which part of the cost of housing is paid by a third party, such as a government.
Reporter Nan Nelson took a great stab at an overview of definitions in a North Coast Citizen article: downloadable PDF.
If you want to know more about the numbers and incomes that define "affordable," "workforce" or "low-income," check out our median income page.