URBAN, a human invention, plays an important role in socio economic development and urbanization is a global trend, although each country has its own distinct concept of urban – rural. The concept of urban population distribution (based on its morphology) has implications for urbanization estimates at the global level, but at the national levels (regardless of their definition) what overall trends in urbanization remain important and countries have the right to define what they consider urban and rural settlements. Urban areas are characterized by densely populated areas, but there are large differences in population density and urban morphology across countries, according to OECD (2020) countries with higher incomes. The higher the density, the lower the density, large cities are more densely distributed than small cities, but in low-income countries, cities of all sizes are very dense. The concept of urban and rural residential areas in large cities in Vietnam (urbanized villages, new urban areas, etc.) has an important meaning in controlling the distribution pattern urban population. This article shares views, concepts and policy recommendations on defining the concept of urban-rural area in the context of the current situation in Vietnamese cities. Keywords: Urbanization; population (POP); population density (POD); urban unit (urban unit); urban functional area.