Subordinators
Subordinators can be used to add variety to the expression of ideas in complex sentences to compare and contrast ideas, concepts, and information. The information which is emphasised is written in the main clause.

whereas
In such cases we may argue that, whereas beginning learners of English need to operate in their second language as much as possible to develop their acquisition of English, more advanced users of English have developed their proficiency to such a level that their native language does not interfere with their writing in English… (Friedlander, 1997:111–112)

while
whilst (more formal)
While time is necessary in order for a treatment to have an effect or for a valid sample of language performance in a naturalistic setting to be collected, the researcher need to be aware of ways in which the research may be negatively affected because it takes place over time (p. 101).

although/though
Although writers did spend nearly 10 minutes longer on their writing task in the match conditions, the log transformation of the raw data indicate that this time difference is not significant (Friedlander, 1997:116).

These subordinators contrast expectations between the information in the adverbial clause and the information in the clause it is dependent on. After the main clause is the more neutral position.