Conjunction is an invariable (non-inflected) grammatical particle that may or may not stand between 

the items conjoined

Coordinating conjunction 

 - Coordinating conjunctions, also called coordinators, are conjunctions that join, or coordinate, two or more items (such as words, main clauses, or sentences) of equal syntactic importance 

examples : For , And , Nor , But , Or , Yet , So 

Correlative conjunction 

-  Correlative conjunctions are pairs of conjunctions that join two or more correlated lexical items within a sentence. There are many different pairs of correlative conjunctions:

either...or

not only...but (also)

neither...nor

both...and

whether...or

just as...so

Subordinating conjunction 

  - Subordinating conjunctions, also called subordinators, are conjunctions that join an independent clause and a dependent clause, and also introduce adverb clauses. The most common subordinating conjunctions in the English language include after, although, as, as far as, as if, as long as, as soon as, as though