Question: I'm looking for something people from rural area would use, especially when they refer to that person's inability to adapt to the country life.

Answer: 
In Cornwall, UK they are often referred to as *[grockles](http://www.oxforddictionaries.com/words/what-is-the-origin-of-the-word-grockle)*, though this refers more to 'tourists' than specifically town dwellers (after all, there *are* some towns in Cornwall...)
**city boy/girl** (disparaging when used to describe an adult)

[Oxford dictionaries](http://www.oxforddictionaries.com/us/definition/american_english/city-boy)

> 
> A boy or man who is a native or inhabitant of a city, or who has urban tastes or manners.
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