An urban area is a whole of gathered plusior aglomeration which forms a large territory called " région" like a small megalopolis. One should not confuse with urban unit and areas urban because in big cities like Paris, Londre, New York the figures between the areas urban and the urban units resemble each other much because these cities have a territory urbanized enormous in surface and with it ya nothing thus the urban unit is taken as a count in his figures as well as the area because with of its mégapoles he there that rural terrtoires thus not of agglomerations in conclusion the areas urban not to extend little in its cities and takes the impression of the population of the urban unit. But Lyon they have are different because the territory is large but not enormous thus urban units " also grande" can sy found all while being separated from that Ci like that of Grenoble. Lyon and Grenoble are two great urban units has proximity but it are separate there are rural landscapes thus the 2 figures cannot have agreement. Lyon has an urban unit of 1500000 inhabitants but its urban areas which comprens the urban units of Grenoble and full with small others to see small communes is of 3200000 inhabitants.