Correct

房间 vs 屋子

/ fángjiān vs wūzi /
Strokes

Definition

房间 and 屋子 both are Noun, which means [room].

Example

房间 usually applies to the room of a big, modern building.
1
Zhèjiā
这家
guǎn
旅馆
gòng
一共
yǒu
shí
几十
fángjiān
房间
  

There are dozens of rooms in the hotel.

屋子 usually refers to rooms of a private house or a small old-fashioned structure. Moreover, 屋子 is commonly used in the north and it is rather colloquial; the southerners usually say 房间.
房间 is not used in example ②, since 四合院 (a compound with houses around a square courtyard) is a typical style of northern structure.
2
Zhège
这个
yuàn
四合院
  
,
yǒu
shí
十几
jiān
zi
屋子
  

There are more than ten rooms in the quadrangle.

房间 and 屋子 are used interchangeably (but with different measure words), when referring to the rooms of a suite nowadays.
3
Xiàngpiàn
相片
zài
de
fángjiān
房间
  
(
zi
屋子
  
)
  
,
kàn
  

The photo is in my room. You can go and have a look at it.

4
de
xīn
新居
  
,
gòng
一共
yǒu
jiān
zi
屋子
  
(
fángjiān
房间
  
)
  

There are four rooms in her new apartment.