Obviously, there are at least two plants in there, possibly three, two blue ones and a white in the middle.

Looks real to me going by the variation in colors which is indicative of different age of blooms and the asymmetric in where all the flowers are positioned.

Definitely created......but using real plants. Those are potted florists' hydrangeas, forced into an early bloom on very young, compact plants and just slipped into a larger planter to provide a short term seasonal effect.

Thank you

You could get the same effect by filling the container with ericaceous mix and planting several shrubs. This would last a couple of years before needing attention, other than pruning and feeding. But remember that all winter you would have a trough full of bare sticks, with dead flowerheads on top. (Providing mopheads even survive a Chicago winter in a container. Do they? )

Alternatively just place pots of plants in the trough and switch them out seasonally.

"Providing mopheads even survive a Chicago winter in a container. Do they?"

Not a chance!!

If you want to recreate that, you could plant an annabelle in the middle and macrophylla's on each side. Keep in mind that soil ph is not the only thing that determines bloom color of macs. You need iron for pink and aluminum for blue. Almost always both be available in the ground. But maybe not in pots. If both are absent, you'll get white blooms. In order to survive winter, you'll probably need to grow them in pots inside the big outside pot and take them inside a garage, shed or cool basement for the winter.

There are white macrophyllas. No need for Anabelle. And white cultivars will remain white whatever the soil pH. Neither pink nor blue macrophyllas will turn white whatever the soil. Some, but not all, pinks can turn blue in acidic soil. https://www.gardening-advice.net/hydrangea-colors.html 

A white macrophylla in a container.

There may be some confusion wrt Hydrangea macrophylla flower color. The determining factor is only aluminum availability. A low pH will allow Al uptake resulting in blue flowers: a higher pH will impede it, resulting in pink flowers. Iron is not a factor. If Al is not adequately present in the soil the macs will bloom pink or purply-red. They will not produce white flowers regardless. White macs are white and pH or aluminum availability has no impact at all.