<p>开心 can be either <strong>joyful, delighted</strong> or <strong>the mood of happiness</strong>.   </p>

<p>快乐 is <strong>the mood of happiness</strong>.  The dictionary defines it as:</p>

<blockquote>
  <p>形容称心如意的心情</p>
</blockquote>

<p>So, we say 我今天玩得很开心，not 我今天玩得很快乐.  </p>

<p>But they can be synonyms as in 和他在一起很开心/快乐. In this case, both denote the sense of <em>the mood of happiness</em>. </p>

CC BY-SA 4.0
2020-01-19T07:19:43.273Z
2020-01-19T07:19:43.273Z
dan
<p>In your case, both 开心 and 快乐 are used as adjectives, which denote “happy”. Translated, the sentence means “I am happy when you are happy.” </p>

<p>However, only 快乐 can also be used as a noun.</p>

<pre><code>“他从做善事当中获得快乐。”
</code></pre>

<p>This would mean “he obtains happiness from doing good deeds”. It would sound weird if you substituted 快乐 with 开心, which would then make it “he obtains happy from doing good deeds.”</p>

CC BY-SA 4.0
2020-01-19T11:28:07.677Z
2020-01-19T11:28:07.677Z
Axel Tong
<p>I think they can be used interchangeably. When it used in songs or poems, rhythm is more important than which word to be used. Sometimes, to avoid using the same word in one sentence, people tend to use a different one too. </p>

CC BY-SA 4.0
2020-01-19T05:59:13.620Z
Is it correct to say 开心 is "happy", and 快乐 is "happiness?“ Like 朋友 is “friend” and  友谊 is “friendship?
Wayne Cheah
CC BY-SA 4.0
2020-01-19T22:33:06.357Z
Right, in some situations. However, it is different from 朋友 and 友谊， because those two words cannot be used interchangeably...
sylvia
CC BY-SA 4.0
2020-01-19T04:59:42.643Z
2020-01-19T04:59:42.643Z
sylvia
<p>Dictionaries will give "Happy" for both.</p>

<p>A Mandarin song has the title 你开心所以我快乐</p>

<p><a href="https://youtu.be/Sb1ojccxvyw" rel="nofollow noreferrer">https://youtu.be/Sb1ojccxvyw</a></p>

<p>Question therefore is whether there is any signifying difference in usage?</p>

<p>That is, which word / phrase fits better in a certain context or situation. </p>

CC BY-SA 4.0
2020-01-19T04:28:57.303Z
"为了押韵歌手们什么都写得出"
Toosky Hierot
CC BY-SA 4.0
2020-01-19T05:50:49.093Z
也就是说, 好听好唱就好?  没那么简单吧？
Wayne Cheah
<meaning><word-choice>
What is the difference, if any, between 开心 and 快乐
# What is the difference, if any, between 开心 and 快乐

(Asked by: username_0 on 2020-01-19)

Dictionaries will give "Happy" for both.

A Mandarin song has the title 你开心所以我快乐

<https://youtu.be/Sb1ojccxvyw>

Question therefore is whether there is any signifying difference in usage?

That is, which word / phrase fits better in a certain context or situation.

**Tags:** meaning, word-choice
> **Comments:**
> **username_1**: "为了押韵歌手们什么都写得出"  
> **username_0**: 也就是说, 好听好唱就好?  没那么简单吧？  

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## 3 answers

### Answer by username_2 on 2020-01-19. Score: 5

开心 can be either **joyful, delighted** or **the mood of happiness**.

快乐 is **the mood of happiness**. The dictionary defines it as:

> 形容称心如意的心情

So, we say 我今天玩得很开心，not 我今天玩得很快乐.

But they can be synonyms as in 和他在一起很开心/快乐. In this case, both denote the sense of *the mood of happiness*.


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### Answer by username_3 on 2020-01-19. Score: 4

In your case, both 开心 and 快乐 are used as adjectives, which denote “happy”. Translated, the sentence means “I am happy when you are happy.” 
However, only 快乐 can also be used as a noun.
“他从做善事当中获得快乐。”

This would mean “he obtains happiness from doing good deeds”. It would sound weird if you substituted 快乐 with 开心, which would then make it “he obtains happy from doing good deeds.”


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### Answer by username_4 on 2020-01-19. Score: 1

I think they can be used interchangeably. When it used in songs or poems, rhythm is more important than which word to be used. Sometimes, to avoid using the same word in one sentence, people tend to use a different one too.

> **Comments:**
> **username_0**: Is it correct to say 开心 is "happy", and 快乐 is "happiness?“ Like 朋友 is “friend” and  友谊 is “friendship?  
> **username_4**: Right, in some situations. However, it is different from 朋友 and 友谊， because those two words cannot be used interchangeably...  

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