user13078: I have seen people using the words Pin ("good deeds") interchangeably with Kusal; and Paw ("bad deeds") interchangeably with Akusal.
But there are clear differences between them -- per my understanding:

Pin (Good deeds) - Actions done physically, verbally or with mind that has good karmas
Kusal - Anything that would lead you in the path to nirvana.

(Paw (Bad deeds) and Akusal are the opposites of the above.)
But I'm not sure about these definitions. I would like to know the exact meaning of these and how they are related to each other?

user10100: Kusala, wholesome, is an advantage mind and mental factors. It is the advantage because it must causes both present and future advantage resultants, KusalaVipāka. 
Kusala can arise without Puññā, i.e. a boy gives a gift to a poor man just on demand, but Puññā can't arise without Kusala because Puññā without Kusala is the ignorant, Aññāṇa. Aññāṇa is the root of Akusalā, unwholesome, and causes the advantage resultants.
Paññā = understand the fact: causes&effects, the dependent origination, Paṭṭhāna.
Paṭivedha = Paññā.
Paṭivedha = understand through the fact relation: causes&effects.
Ñāṇa = Expert Paññā.
Dassana = View, Understood, Diṭṭhi (vision), Cakkhu (eye).

user14809: See puñña and kusala, Nyom Achala Dissanayake
And no, it's not right to say that all kusala is or leads to the, or is on the path. The word Puñña, in and of it self, as well.
Both words should be seen in relation to the world and/or beyound, can be used for very worldily thing as well.
Puñña actually (lit.) means what gives/makes joy (long term).
Kusala: ku (wrong) sala (uproots, cuts off) => that what uproots bad (in ones heart)
See also the different kinds of kamma, kusala on the path included: Ariyamagga Sutta: The Noble Path
And what kinds of puñña are there?

កាលទានសូត្រ - Question about Dana
[៦០] ខ្ញុំ​បាន​ស្ដាប់​មក​ថា ពាក្យ​នុ៎ះ ព្រះ​មាន​ព្រះ​ភាគ ទ្រង់​ត្រាស់​ហើយ ព្រះ​អរហន្ត​សំដែង​ហើយ។ ម្នាល​ភិក្ខុ​ទាំង​ឡាយ បុញ្ញ​កិរិយា​វត្ថុ​នេះ មាន ៣។ បុញ្ញ​កិរិយា​វត្ថុ ៣ តើ​ដូច​ម្ដេច។ គឺ​ទានមយបុញ្ញ​កិរិយា​វត្ថុ ១ សីលមយបុញ្ញ​កិរិយា​វត្ថុ ១ ភាវនាមយបុញ្ញ​កិរិយា​វត្ថុ ១។ ម្នាល​ភិក្ខុ​ទាំង​ឡាយ បុញ្ញ​កិរិយា​វត្ថុ មាន ៣ នេះ​ឯង។
លុះ​ព្រះ​មាន​ព្រះ​ភាគ ទ្រង់​សំដែង​សេចក្ដី​នុ៎ះ​ហើយ។ ទ្រង់​ត្រាស់​គាថា​ព័ន្ធ​នេះ ក្នុង​សូត្រ​នោះ​ថា
កុលបុត្រ​អ្នក​ប្រាថ្នា​ប្រយោជន៍ គួរ​សិក្សានូវ​បុណ្យ ដែល​មានផល​បរិបូណ៌ មាន​វិបាកជា​សុខ គឺគួរ​ចំរើន​ទានផង ការ​ប្រព្រឹត្តិស្មើ គឺ​សីលផង មេត្តា​ចិត្ត​ផង លុះ​ចំរើន​ធម៌​ទាំង ៣ នេះ ដែល​មាន​អានិសង្ស​ជា​សុខ​ហើយ រមែង​ចូល​ទៅ​កាន់​លោក ដែល​ជា​សុខ ឥតមាន​ការបៀតបៀន។
ខ្ញុំ​បាន​ស្ដាប់​មក​ហើយ​ថា សេចក្ដី​នេះ​ឯង ព្រះ​មាន​ព្រះ​ភាគ បាន​ត្រាស់​ទុក​ហើយ។

What ever kusala or puñña is not based on "maha-metta", means is not based on right view, has no foot on the path to Nibbana for now.
[This gift, not given for trade, exchange or stacks, and commercial purpose, should be deleted is shares for liberation are against the owners objectives]

user111: Pin(Punya) and Kusal are both same. Pin means that which purifies the mind. Kusala means that which is born of wisdom or that which counters defilements. The good deeds that lead to birth in heavenly realms are called Wattagamini-Kusala and the good deeds that lead to Nibbana are called Viwattagamini-Kusala. Here's an explanation by ven. Nauyane Ariyadhamma Thera.

13078: <p>I have seen people using the words <em>Pin</em> ("good deeds") interchangeably with <em>Kusal</em>; and <em>Paw</em> ("bad deeds") interchangeably with <em>Akusal</em>.</p>

<p>But there are clear differences between them -- per my understanding:</p>

<ul>
<li><p><em>Pin</em> (Good deeds) - Actions done physically, verbally or with mind that has good karmas</p></li>
<li><p><em>Kusal</em> - Anything that would lead you in the path to nirvana.</p></li>
</ul>

<p>(<em>Paw</em> (Bad deeds) and <em>Akusal</em> are the opposites of the above.)</p>

<p>But I'm not sure about these definitions. I would like to know the exact meaning of these and how they are related to each other?</p>
 10100: <p><strong>Kusala, wholesome,</strong> is an advantage mind and mental factors. It is the advantage <strong>because it must causes both present and future advantage resultants, KusalaVipāka.</strong> </p>

<p><strong>Kusala can arise without Puññā</strong>, i.e. a boy gives a gift to a poor man just on demand, <strong>but Puññā can't arise without Kusala</strong> because Puññā without Kusala is the ignorant, Aññāṇa. Aññāṇa is the root of Akusalā, unwholesome, and causes the advantage resultants.</p>

<p><strong>Paññā</strong> = understand the fact: causes&amp;effects, the dependent origination, Paṭṭhāna.</p>

<p>Paṭivedha = Paññā.</p>

<p>Paṭivedha = understand through the fact relation: causes&amp;effects.</p>

<p>Ñāṇa = Expert Paññā.</p>

<p>Dassana = View, Understood, Diṭṭhi (vision), Cakkhu (eye).</p>
 14809: <p>See <a href="http://accesstoinsight.eu/en/dictionary/punna" rel="nofollow noreferrer">puñña</a> and <a href="http://accesstoinsight.eu/en/dictionary/kusala" rel="nofollow noreferrer">kusala</a>, Nyom Achala Dissanayake</p>
<p>And no, it's not right to say that all kusala is or leads to the, or is on the path. The word <em>Puñña</em>, in and of it self, as well.</p>
<p>Both words should be seen in relation to the world and/or beyound, can be used for very worldily thing as well.</p>
<p><em>Puñña</em> actually (lit.) means what gives/makes joy (long term).
<em>Kusala</em>: <em>ku</em> (wrong) <em>sala</em> (uproots, cuts off) =&gt; that what uproots bad (in ones heart)</p>
<p>See also the different kinds of kamma, kusala on the path included: <a href="http://zugangzureinsicht.org/html/tipitaka/an/an04/an04.235.than_en.html" rel="nofollow noreferrer">Ariyamagga Sutta: The Noble Path</a></p>
<p>And what kinds of puñña are there?</p>
<blockquote>
<p><a href="http://sangham.net/index.php/topic,8983.msg16684.html#msg16684" rel="nofollow noreferrer">កាលទានសូត្រ - Question about Dana</a></p>
<p>[៦០] ខ្ញុំ​បាន​ស្ដាប់​មក​ថា ពាក្យ​នុ៎ះ ព្រះ​មាន​ព្រះ​ភាគ ទ្រង់​ត្រាស់​ហើយ ព្រះ​អរហន្ត​សំដែង​ហើយ។ ម្នាល​ភិក្ខុ​ទាំង​ឡាយ បុញ្ញ​កិរិយា​វត្ថុ​នេះ មាន ៣។ បុញ្ញ​កិរិយា​វត្ថុ ៣ តើ​ដូច​ម្ដេច។ គឺ​ទានមយបុញ្ញ​កិរិយា​វត្ថុ ១ សីលមយបុញ្ញ​កិរិយា​វត្ថុ ១ ភាវនាមយបុញ្ញ​កិរិយា​វត្ថុ ១។ ម្នាល​ភិក្ខុ​ទាំង​ឡាយ បុញ្ញ​កិរិយា​វត្ថុ មាន ៣ នេះ​ឯង។</p>
<p>លុះ​ព្រះ​មាន​ព្រះ​ភាគ ទ្រង់​សំដែង​សេចក្ដី​នុ៎ះ​ហើយ។ ទ្រង់​ត្រាស់​គាថា​ព័ន្ធ​នេះ ក្នុង​សូត្រ​នោះ​ថា</p>
<p>កុលបុត្រ​អ្នក​ប្រាថ្នា​ប្រយោជន៍ គួរ​សិក្សានូវ​បុណ្យ ដែល​មានផល​បរិបូណ៌ មាន​វិបាកជា​សុខ គឺគួរ​ចំរើន​ទានផង ការ​ប្រព្រឹត្តិស្មើ គឺ​សីលផង មេត្តា​ចិត្ត​ផង លុះ​ចំរើន​ធម៌​ទាំង ៣ នេះ ដែល​មាន​អានិសង្ស​ជា​សុខ​ហើយ រមែង​ចូល​ទៅ​កាន់​លោក ដែល​ជា​សុខ ឥតមាន​ការបៀតបៀន។</p>
<p>ខ្ញុំ​បាន​ស្ដាប់​មក​ហើយ​ថា សេចក្ដី​នេះ​ឯង ព្រះ​មាន​ព្រះ​ភាគ បាន​ត្រាស់​ទុក​ហើយ។</p>
</blockquote>
<p>What ever kusala or puñña is not based on &quot;maha-metta&quot;, means is not based on right view, has no foot on the path to Nibbana for now.</p>
<p><em>[This gift, not given for trade, exchange or stacks, and commercial purpose, should be deleted is shares for liberation are against the owners objectives]</em></p>
 111: <p>Pin(Punya) and Kusal are both same. Pin means that which purifies the mind. Kusala means that which is born of wisdom or that which counters defilements. The good deeds that lead to birth in heavenly realms are called Wattagamini-Kusala and the good deeds that lead to Nibbana are called Viwattagamini-Kusala. Here's an <a href="https://www.youtube.com/watch?v=w3wXxZryusI" rel="nofollow noreferrer">explanation by ven. Nauyane Ariyadhamma Thera</a>.</p>
