They are not the same as conjunctions and/or articles.
Prepositions: A word that indicates the temporal, spatial, or logical relationship of an object to the rest of the sentence. (eg.: book ON table, pencil UNDER book, tools used DURING class)
Conjunctions: A word or series of words that connect parts of a compound sentence. (eg.: I'm a vegetarian BUT I eat seafood, He studied hard SO he got an A, She does not dance NOR does she sing)
Articles: A word used with a noun to indicate and/or limit the type of reference being made by the noun. (eg.: A bicycle, AN apple, THE classroom)