How to say "a small market centre" in Korean?
Context:
Suppose I go to one of the provinces of Korea such as 강진군.
I take a bus from 광주광역시 in 전라도 and reach the bus terminal at 강진.
What is the Korean word for the business centre at the location of the bus terminal in 강진?
I think this place is not a 도시 (or is it?) so would it be called a 시내?
Should this place be called 시내/시장/상가/something else?
Also, how do I differentiate a place like this from the outskirts of a big city such as 광주? Can I use 시골 for both of them?

Question

Answer

Excerpts from wikipedia.org;

'South Korea is divided into 8 provinces (do 도/道), 1 special autonomous province (teukbyeol jachido 특별자치도/特別自治道), 6 metropolitan cities (gwangyeoksi 광역시/廣域市), and 1 special city (teukbyeolsi 특별시/特別市). 
These are further subdivided into a variety of smaller entities, including 
cities (si 시/市), 
counties (gun 군/郡), 
districts (gu 구/區), 
towns (eup 읍/邑), 
townships (myeon 면/面), 
neighborhoods (dong 동/洞) and 
villages (ri 리/里)".

If an administrative unit has large population and  urban center function, it is recognized as 시. If not, 군.

강진군, with the population of 49,000, has one 읍(the business center) and 10 면.
읍 is called as 읍내 also,

(At the 광주 버스 터미널)
old man: 어디 가나, 젊은이?(where are you headed?)
young man:강진이요.
O: 시골은 왜 가? (compared relatively)
Y: 친구 만나러요.
O: 친구가 어디 사는데?
Y: 파산-리라고 하던데요.
O: 파산-리는 군동-면에 있어. 완전 시골이야.
Y;: 강진 버스 터미널 앞에 있는 시장에서 만나기로 했어요.
O: 아, 시내에서 만나기로 했군? 친구 만나면 우리 가게 놀러 와.
Y: 할아버지 가게 어디 있는데요?
O: 시장 근처에 있는 상가야.
Y: 네, 꼭 갈게요. 저는 도시보다 시골이 짱 좋아요!

By the way, do you speak Korean? -,.-"