Correct

开动 vs 发动

/ kāidòng vs fādòng /
Strokes

Definition

开动 and 发动 both are Verbs, which means [start; set in motion; launch].

Example

开动 and 发动 both Verbs means "to set a machine in motion".
1
Yìnshuā
印刷机
kāidòng
开动
  
(
dòng
发动
  
)
lai
起来
le
  

The printing press started.

开动 stresses "to start motion", while 发动 stresses "the process of operation through ignition".
2
Tiānhándòng
天寒地冻
  
,
chē
汽车
hǎo
róng
容易
cái
dòng
发动
lai
起来
  

It was not easy to start the car for it was freezing.

开动 can be used figuratively to mean "using one's brain, etc.". For instance, in colloquial speech one can say.
3
jiā
大家
yào
积极
kāidòng
开动
nǎojīn
脑筋
xiǎng
bàn
办法
  

Everyone is racking his or her brain to find a way.

开动 can also mean "to be on the move of the troop or traffic".
4
Duì
队伍
xiūxi
休息
le
huìr  
一会儿
jiù
kāidòng
开动
le
  

The troops were on the move again after a short rest.

5
Huǒchē
火车
kāidòng
开动
le
  

The train has started.

发动 can mean "to start a war".
6
Qīnlüèzhě
侵略者
dòng
发动
le
zhànzhēng
战争
  

The invaders launched the war.

发动 can also mean "to mobilize people to engage in a campaign (usually of a big scale)".
7
Xiàn
县里
dòng
发动
le
大批
míngōng
民工
kànghóng
抗洪
qiǎngxiǎn
抢险
  

The county government mobilizes a body of civilian workers to fight against the floods.

8
Chǎngzhǎng
厂长
dòng
发动
qīngnián
青年
gōngrén
工人
zài
chǎngfáng
厂房
zhōuwéi
周围
zhíshù
植树
  

The director of the factory called up young workers to plant trees around the factory compound.