Adjectives can be divided into two categories:
- qualitative
- classifying
Qualitative adjectives 
Qualitative adjectives give information about the qualities of the noun they modify.
Examples are:
big, hungry,
an intelligent student,
a highly intelligent student,
a fairly intelligent student.
The use of highly and fairly makes an extremely big difference to the meaning.
Qualitative adjectives can also be comparative or superlative.
Classifying adjectives
Classifying adjectives place the noun into a class or category such as pregnant, annual, and western.  
Other examples of classifying adjectives are:
alternative, communist, 
daily, double, electric, 
internal, potential, standard.