Correct

艰难 vs 困难

/ jiānnán vs kùnnan /
Strokes

Definition

艰难 as an Adjective, and 困难 as a Noun or Adjective, which means [difficult; difficulty; arduous], indicate "complication, resistance, predicament, poverty-stricken, etc".

Example

The scale and degree of difficulties denoted by 艰难 surpass those of 困难. Sometimes 艰难 refers in particular to the great hardships in starting an undertaking.
1) The noun 困难 has the same meaning as the adjective and can function as the subject or object of a sentence.

2) We usually say 有困难 (have difficulty), 遇到了困难 (encountered difficulties), 克服困难 (overcome difficulties), 困难不小 (a big difficulty), etc. While 艰难 is usually found in phrases like 艰难困苦 (difficulties and hardships), 艰难险阻(hardships and dangers), etc.

3) In the sentences, the two words are not interchangeable.
1
xué
科学
shì
事业
shì
xiàng
shí
fēn
jiānnán
艰难
de
shì
事业
  
,
必须
jiǎoshi
脚踏实地
gàn
  
,
méiyǒu
没有
jiéjìng
捷径
zǒu
  

The scientific work is full of hardships,and there is no shortcut in it,so we must work steadily and patiently.

2
zhège
这个
rén
hěn
yǒu
rènxìng
韧性
  
,
rèn
任何
jiānnánkùn
艰难困苦
dōu
dǎng
zhù
不住
  

He is tenacious,and can overcome every hardship and difficulty.

3
zài
zuò
zuo
作业
de
guòchéng
过程
zhōng
dào
遇到
le
xiē
一些
kùnnan
困难
  
,
dàn
dōu
一一
克服
le
  

He had some difficulties in his homework,and he overcome them one by one.

4
shì
shàn
善于
克服
kùnnan
困难
de
rén
  

He can overcome difficulties with ease.

When talking about a hard life or a life suffering from financial problems, either word can be used, but 艰难 sounds more intensified than 困难.
5
Cóngqián
从前
men
他们
jiā
de
zi
日子
hěn
jiānnán
艰难
  
(
kùnnan
困难
  
)
  

Their family had a hard time before.

6
jiù
shī
失业
le
  
,
méiyǒu
没有
shōu
收入
  
,
shēnghuó
生活
de
hěn
jiānnán
艰难
  
(
kùnnan
困难
  
)
  

He was unemployed, had no income, and lived a difficult life.

When applied to more serious events, either word will do; but there is still a difference in degree, 艰难 is harder then 困难.
7
zhège
这个
ànzi
案子
  
,
jìnxíng
进行
de
shí
fēn
jiānnán
艰难
  
(
kùnnan
困难
  
)
  

The case he accepted is difficult to carry out.

8
Zhè
shì
jiānnán
艰难
  
(
kùnnan
困难
  
)
ér
zhé
曲折
de
xíng
旅行
  

It was a difficult and roundabout trip.