user471: What is the relationship between the definitions of sampajañña (clear comprehension) in SN 47.2 and SN 47.35?
From SN 47.35 (translated by Bodhi):

“And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here,
  bhikkhus, for a bhikkhu feelings are understood as they arise,
  understood as they remain present, understood as they pass away.
  Thoughts are understood as they arise, understood as they remain
  present, understood as they pass away. Perceptions are understood as
  they arise, understood as they remain present, understood as they pass
  away. It is in this way, bhikkhus, that a bhikkhu exercises clear
  comprehension.

From SN 47.2 (translated by Bodhi):

“And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here,
  bhikkhus, a bhikkhu is one who acts with clear comprehension when
  going forward and returning; when looking ahead and looking aside;
  when drawing in and extending the limbs; when wearing his robes and
  carrying his outer robe and bowl; when eating, drinking, chewing his
  food, and tasting; when defecating and urinating; when walking,
  standing, sitting, falling asleep, waking up, speaking, and keeping
  silent. It is in such a way that a bhikkhu exercises clear
  comprehension.


user8157: 
And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here, bhikkhus, for a bhikkhu feelings are understood as they arise,
  understood as they remain present, understood as they pass away.
  Thoughts are understood as they arise, understood as they remain
  present, understood as they pass away. Perceptions are understood as
  they arise, understood as they remain present, understood as they pass
  away. It is in this way, bhikkhus, that a bhikkhu exercises clear
  comprehension.
SN 47.35

The above means feelings, perceptions & thoughts are clearly understood in terms of the Dhamma, namely, they are impermanent, not-self, not to be clung to. 
Note: This is not vipassana, namely, observing arising & passing of feelings, perceptions & thoughts. It is understanding feelings, perceptions & thoughts, including when they are purposefully used. Thus, when speaking to another, for example, the mind understands: "These thoughts are conventions, subjective, not to be clung to, etc". 

And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here, bhikkhus, a bhikkhu is one who acts with clear comprehension when
  going forward and returning; when looking ahead and looking aside;
  when drawing in and extending the limbs; when wearing his robes and
  carrying his outer robe and bowl; when eating, drinking, chewing his
  food, and tasting; when defecating and urinating; when walking,
  standing, sitting, falling asleep, waking up, speaking, and keeping
  silent. It is in such a way that a bhikkhu exercises clear
  comprehension.
SN 47.2

The above is exactly the same. When walking, the monk has clear-comprehension, such as: "I am monk; I must walk so I make a good public impression" or "I am a monk; I must eat non-hurriedly; so I make a good public impression"; or the monk reflects: "This walking is not self" (such as when Rahula was walking behind the Buddha in MN 62 and the Buddha rebuked Rahula for regarding the Buddha as a "self" or with "beauty"). 

user43: In line with what I said in my other answer, both are descriptions of self-awareness, of not getting carried away by the circumstances.
This does not refer to "zombie bare awareness" executed mechanically, but to normal, pragmatic, careful self-awareness of an intelligent person. 

471: <p>What is the relationship between the definitions of <em>sampajañña</em> (clear comprehension) in SN 47.2 and SN 47.35?</p>

<p>From <a href="https://suttacentral.net/sn47.35/en/bodhi" rel="nofollow noreferrer">SN 47.35</a> (translated by Bodhi):</p>

<blockquote>
  <p>“And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here,
  bhikkhus, for a bhikkhu feelings are understood as they arise,
  understood as they remain present, understood as they pass away.
  Thoughts are understood as they arise, understood as they remain
  present, understood as they pass away. Perceptions are understood as
  they arise, understood as they remain present, understood as they pass
  away. It is in this way, bhikkhus, that a bhikkhu exercises clear
  comprehension.</p>
</blockquote>

<p>From <a href="https://suttacentral.net/sn47.2/en/bodhi" rel="nofollow noreferrer">SN 47.2</a> (translated by Bodhi):</p>

<blockquote>
  <p>“And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here,
  bhikkhus, a bhikkhu is one who acts with clear comprehension when
  going forward and returning; when looking ahead and looking aside;
  when drawing in and extending the limbs; when wearing his robes and
  carrying his outer robe and bowl; when eating, drinking, chewing his
  food, and tasting; when defecating and urinating; when walking,
  standing, sitting, falling asleep, waking up, speaking, and keeping
  silent. It is in such a way that a bhikkhu exercises clear
  comprehension.</p>
</blockquote>
 8157: <blockquote>
  <p><em>And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here, bhikkhus, for a bhikkhu feelings are understood as they arise,
  understood as they remain present, understood as they pass away.
  Thoughts are understood as they arise, understood as they remain
  present, understood as they pass away. Perceptions are understood as
  they arise, understood as they remain present, understood as they pass
  away. It is in this way, bhikkhus, that a bhikkhu exercises clear
  comprehension.</em></p>
  
  <p><em>SN 47.35</em></p>
</blockquote>

<p>The above means feelings, perceptions &amp; thoughts are clearly understood in terms of the Dhamma, namely, they are impermanent, not-self, not to be clung to. </p>

<p>Note: This is not vipassana, namely, observing arising &amp; passing of feelings, perceptions &amp; thoughts. It is understanding feelings, perceptions &amp; thoughts, including when they are purposefully used. Thus, when speaking to another, for example, the mind understands: "<em>These thoughts are conventions, subjective, not to be clung to, etc</em>". </p>

<blockquote>
  <p><em>And how, bhikkhus, does a bhikkhu exercise clear comprehension? Here, bhikkhus, a bhikkhu is one who acts with clear comprehension when
  going forward and returning; when looking ahead and looking aside;
  when drawing in and extending the limbs; when wearing his robes and
  carrying his outer robe and bowl; when eating, drinking, chewing his
  food, and tasting; when defecating and urinating; when walking,
  standing, sitting, falling asleep, waking up, speaking, and keeping
  silent. It is in such a way that a bhikkhu exercises clear
  comprehension.</em></p>
  
  <p><em>SN 47.2</em></p>
</blockquote>

<p>The above is exactly the same. When walking, the monk has clear-comprehension, such as: "<em>I am monk; I must walk so I make a good public impression</em>" or "<em>I am a monk; I must eat non-hurriedly; so I make a good public impression</em>"; or the monk reflects: "<em>This walking is not self</em>" (such as when Rahula was walking behind the Buddha in MN 62 and the Buddha rebuked Rahula for regarding the Buddha as a "self" or with "beauty"). </p>
 43: <p>In line with what I said in my other answer, both are descriptions of self-awareness, of not getting carried away by the circumstances.</p>

<p>This does not refer to "zombie bare awareness" executed mechanically, but to normal, pragmatic, careful self-awareness of an intelligent person. </p>
