Correct

预先 vs 事先

/ yùxiān vs shìxiān /
Strokes

Definition

预先 is an Adverb, and 事先 is a Noun, which means [in advance; beforehand].

Example

预先 and 事先, both the two words mean "before an event or action happens", they are adverbials and interchangeable.
1
yīnggāi
应该
xiān
预先
  
(
shìxiān
事先
  
)
gào
告诉
yào
yán
发言
  
,
可以
zhǔnbèi
准备
xià
  

You should inform me that I will deliver a speech in advance, so I can prepare it.

2
zhīdào
知道
ge
那个
fāng
地方
ài
xià
下雨
  
,
suǒ
所以
xiān
预先
  
(
shìxiān
事先
  
)
mǎi
le
jiàn
雨衣
  

He knew it was rainy there, so he bought a raincoat in advance.

3
yīnggāi
应该
xiān
预先
  
(
shìxiān
事先
  
)
zhāohu
招呼
  

You should have told us in advance.

4
xiān
预先
  
(
shìxiān
事先
  
)
zuò
le
xiē
一些
diàochá
调查
  

He conducted some survey in advance.

The difference is in that 预先 stresses the conscious preparation before a thing happens, while 事先 has no such meaning. Therefore, as for unpredictable things, 预先 can not replace 事先.
5
zhèn
地震
fēicháng
非常
ǒurán
偶然
  
,
shìxiān
事先
háo
毫无
xiàng
迹象
  

The earthquake took place beyond our expectation, for there's no sign at all before it.

6
Duì
zhè
这次
dōngnán
东南亚
jīnróng
金融
wēi
危机
  
,
lǎobǎixìng
老百姓
shìxiān
事先
dōu
háo
毫无
xīn
心理
zhǔnbèi
准备
  

All the civilians didn't expected the South Asian financial crisis.

事先 is a Noun and can be used as an attributive with 的; while 预先 is an adverb and can only be used as an adverbial.
7
shìxiān
事先
de
tàidu
态度
gēn
xiànzài
现在
zhènghǎo
正好
xiāngfǎn
相反
  

His attitude is different from his previous one.

8
Zhè
shì
shìxiān
事先
de
ānpái
安排
  

This is prearranged.

Related

预先事先