From the time they take their first breath, and even in utero, babies begin developing what are called motor skills. Motor skills are basically learned muscular movements that develop and improve with time and practice.
Divided into two groups, motor skills can be fine (the coordination of small muscles) or gross (the coordination of larger muscles). Researchers studying in the field of child development were curious about whether or not a child's environment (countryside living or city living) has an effect on how fast motor skills develop, so they conducted a study to see. The results deemed quite interesting, yet not necessarily surprising.
The main takeaway from the study was that motor skills are quicker to develop and enhance the more time is spent outdoors doing physical activity and exploration. Children living in the countryside, on average, spend more time outside in the woods climbing trees, steep inclines, and running around. Nature acts as a child's classroom for both mind and body alike.
By immersing a child in that environment, they are given more chances to practice using their muscles and therefore their motor development advances more rapidly.
Although children growing up in cities may not have the same sort of advantage when it comes to being able to run free and explore on a daily basis, cities do offer some activities such as organized sports that do account for some major development in the motor skills area.
Another aspect of city living that this particular study doesn't touch on, but other research shows, is the use of electronics. Children growing up in cities are more likely to spend their days using different devices which are actually taking time away from them developing necessary lifelong motor skills.
If, like a lot of people, the countryside setting is more of a place to visit rather than live, allowing your child to explore his/her own skill set in a safe environment in which they can run and roam freely is their best bet at being able to develop on par (bonus if this setting includes fresh air).
Where you live doesn't necessarily mean that your child is at an advantage/disadvantage. It all depends on what you offer for mental and physical stimulation.