What is the differnece between these two words.
I am confused about these two Kanji-温かい and 暖かい。
I am reading Breaking Into Japanese Literature and I am reading the story The First Night by Sōseki. In the book these kanji are used and they are both defined as warm. What is the difference? I wrote the sentences.
真っ白な頬の底に温かいの血色ごほどよく差して唇の色が無論赤い。

。。。自分の胸と手が少し暖くなった。

Question

What is the differnece between these two words.
I am confused about these two Kanji-温かい and 暖かい。
I am reading Breaking Into Japanese Literature and I am reading the story The First Night by Sōseki. In the book these kanji are used and they are both defined as warm. What is the difference?  I wrote the sentences. 
真っ白な頬の底に温かいの血色ごほどよく差して唇の色が無論赤い。

。。。自分の胸と手が少し暖くなった。

Answer

Both 温かい and 暖かい mean the temperature being relatively high. 

The difference is, 
温かい means the warmth physically measured. 
暖かい means the warmth as subjective feeling. 

1.真っ白な頬の底に温かいの血色ごほどよく差して唇の色が無論赤い。 

This is describing other persons face. So it is not proper to use 暖かい, because you don't know how others feel. 

2. 。。。自分の胸と手が少し暖くなった。 

This is describing the feeling that one subjectively felt his/her 胸 and 手 got a little warmer. So it is proper to use 暖かい. 

For reference, 
温かい, 熱い and 冷たい belong to the same group, as physical temperature. 
暖かい, 暑い and 寒い belong to another group, as subjective feeling for temperature. 

※I modified the explanations of 1 and 2 for easier understanding.