The Ministry of Higher and Secondary Specialized Education

Semasiology (deals with all possible meaning of word);

Word-Formation ( studies all possible ways of the formation of new words in English);

3. Etymology (studies the origin of words);

4. 
   Phraseology (studies the set expressions, phraseologycal units);
   
5. 
   Lexicography (studies compiling dictionaries);
   

Lexicography, that is the theory and practice of compiling dictionaries, is an important branch of applied linguistics.
The essential difference between the two lies in the degree of
systematization and completeness each of them is able to achieve.
Lexicology studies recurring patterns of semantic relationships and of any
formal phonological or grammatical devices by which they may be
rendered. It aims at systematization revealing characteristic features of
words and he main opposition relevant for the vocabulary.
It cannot, however, claim any completeness as regards the units
themselves, because the number of this units being very great,
systematization and completeness could be not achieved simultaneously.
The province of lexicography, on the other hand, is the semantic, formal
and functional description of all individual words. Dictionaries aim at a
more or less complete description, but in so doing cannot attain systematic
treatment, so that every dictionary entry presents, as it were, an
independent problem. Lexicologists sort and present their material
in a sequence depending upon their views concerning the vocabulary, whereas lexicographers have to arrange it most often according to a purely external characteristics, namely alphabetically.
Lexicography depends on its development in the solution of some general problems of lexicology. So, lexicography is closely connected with the problems differently. For example, there is no clear border-line between homonymy and polysemy in different dictionaries. Thus in some dictionaries words such as fly- pashsha (Myxa), (a two winged insect) and fly - tugma uchun material ( a flap of cloth covering the buttons on a garment) are treated as two different words and in others ( example: The Concise Oxford Dictionary and the Advanced learners Dictionary of Current English) - as a different meanings of one of the same word.
In conclusion I can say that, lexicography is an important branch of linguistics, particularly of applied linguistics. And it is one of the branches of lexicology. The essential difference between the two lies in the degree of systematization and completeness each of them is able to achieve.