Correct

重要 vs 要紧

/ zhòngyào vs yàojǐn /
Strokes

Formula

1
重要 + 性

Definition

重要 and 要紧 both are Adjectives, which means [important; urgent].

Example

重要 means "to have important bearing or influence", is applied to people or things, and can function as attributive or predicate.
3)重要 can take 性(suffix used to denote a category to become a noun:
4)In all the examples above,要紧 cannot replace 重要.
1
Jīntiān
今天
guǎng
广播
diàntái
电台
jiāng
sòng
播送
zhòngyào
重要
xīnwén
新闻
  

The radio station will broadcast important news today.

2
Zhège
这个
fāng
地方
  
,
zhànlüè
战略
wèi
地位
shí
fēn
zhòngyào
重要
  

The place has an important strategic position.

3
Zhè
běn
cānkǎoshū
参考书
tài
zhòngyào
重要
le
  
,
dìng
一定
yào
mǎi
  

The reference book is very important,so I must buy it.

4
Jīntiān
今天
de
huì
大会
jiāng
yǒu
zhòngyào
重要
lǐngdǎorén
领导人
cānjiā
参加
  

There are important leaders to attend the meeting today.

重要 can take 性 (suffix used to denote a category) to become a Noun.
重要 + 性
5
Yīngdāng
应当
chōngfèn
充分
rènshi
认识
huánjìng
环境
bǎo
保护
de
zhòngyào
重要
xìng
  

The importance of environmental protection should be fully realized.

要紧 means "important, urgent, serious" and functions as attributive, predicate, etc., and 要紧 can be replaced by 重要.
But 要紧 sounds more serious than 重要 and implies a sense of urgency.
6
lái
diànhuà
电话
shuō
yǒu
yàojǐn
要紧
  
(
zhòngyào
重要
  
)
de
shì
zhǎo
  

He phoned me that he had something important to talk over with me.

7
Duì
láishuō
来说
  
,
xiànzài
现在
zuì
yàojǐn
要紧
  
(
zhòngyào
重要
  
)
de
shì
xiūxi
休息
  

As for you, the most important thing is to take a rest.

8
Āi
哎呀
  
,
zuì
yàojǐn
要紧
  
(
zhòngyào
重要
  
)
de
yàng
一样
dōng
东西
  
,
wàng
le
mǎi
le
  

My goodness! I forget to buy the most important item.

要紧 means "serious, critical", and cannot be replaced by 重要.
9
de
bìng
yàojǐn
要紧
ma
  
?

Is his illness serious?

10
Biè
dānxīn
担心
  
,
yàojǐn
不要紧
  
,
可以
自己
huíjiā
回家
  

It doesn't matter, and don't worry about me. I can go home by myself.

11
机器
shàng
shǎo
le
luódīng
螺丝钉
  
,
yàojǐn
要紧
yàojǐn
不要紧
ya
  
?

Does it matter that a screw in the machine is missing?