Difference between ' Small ' & ' Little '

source: Learn English with Let's Talk  2013年09月12日
# 'Small' is used
1. to talk about 'height' or 'size'
--John is small for his age. (He isn't tall enough for his age.)
--The box is small. (it is describing its size).
2. with nouns :
--I have a small amount of wine.
(always use 'amount' for 'uncountable nouns')
--A small number of people came to work.
(always use 'number' with 'countable nouns')
3. in Comparative and Superlative forms :
--Mary is smaller than John. ('smaller' is the comparative form)
--Mary is the smallest girl in the class. ('smallest' is the superlative form)
# 'Little' is
1. similar to young:
--Maria is a little girl. (It describes her of being 'young.')
2. used with 'uncountable nouns':
--I have a little wine every night.
--I had a little trouble with my car.
In the above two example, 'wine' and 'trouble' are uncountable nouns. 'Little' is used only with 'uncountable nouns' when you want to say 'not enough'.
3. used to talk about the Degree of Adjective: There are no 'comparative' and 'superlative' forms of 'little'.
--She is a little fat.
--John is a little tired.
In the above two examples, 'fat' and 'tired' are adjectives (describing words), 'little' is used to modify the adjectives so as to imply 'not too much'.