Written English generally has a much denser pattern of words, it is more lexically dense. If we define lexical density as the number of content words in a clause, then written English has a higher lexical density than spoken English (Halliday, 1996, p. 347).
For example, the written text:
Obviously the government is frightened of union reaction to its move to impose proper behaviour on unions.
is more lexically dense than the spoken version:
Obviously the government is frightened how the unions will react if it tries to make them behave properly.