What's the difference between 'small' and 'little'?

This is a question that I answered on Quora.com. Someone asked "What is the difference between 'small' and 'little'?" Here is what I wrote:

This english.stackexchange page has a detailed discussion of the difference between 'little' and 'small': Difference between "little" and "small"

Also, when thinking about words which are synonyms of each other, it may be helpful to think not in terms of "What's the difference in meaning?" but "Are there differences in how these are used?" In other words, what other words and phrases does each word pair with?

Here are the top 10 collocates (words that appear nearby) for 'little' according to the Corpus of Contemporary American English (COCA): 

1. bit
2. girl
3. boy
4. nervous
5. cute
6. precious
7. incentive
8. resemblance
9. mermaid
10. bitty

(I left out the words "Rock" and "Ark" from the list because they're mostly related to the U.S. city of Little Rock, Arkansas.)

And here are the top collocates for 'small':

1. town
2. business
3. relatively
4. bowl
5. amount
6. size
7. percentage
8. pieces
9. sample
10. farmers

You can get a sense of the difference in usage between "little" and "small" based on these lists, even though they mean essentially the same thing.

In general, I think it's better to think about differences in usage between similar words instead of differences in meaning.