Conjunction and a Preposition both are words which represent a relationship between two or more words. The main difference between the two is that a preposition is always followed by a noun, pronoun, or complement, whereas a conjunction can be followed by any of the above or by another conjunction. There are many similarities between conjunctions and prepositions but there are also significant differences. One of the main differences between these two parts of speech is that prepositions can’t stand alone in a sentence whereas conjunctions can.

Conjunctions are words which help you express a relationship between two things. They are mainly used to show the connection between two ideas or two parts of a sentence.

There are many conjunctions in English but these can be divided broadly into two categories which includes Coordinating conjunctions and Subordinating conjunctions . All conjunctions have same pattern for their conjugation i.e. If the word ‘and’ is conjugated, then all other conjunctions are also conjugated in the same way.

Conjunction + and + verb + complement/noun

Ex: I am sure that I will pass the exam. (that is used as a conjunction)

A preposition is a conjunction which is used to show the relationship between a noun or pronoun and another word in a sentence. It is always accompanied by an object. The prepositions are mainly used in phrases, clauses or sentences.

Examples of Prepositions are: In, on, under , after, across , Except etc..

When prepositions are used with conjunction it is called Coordinating conjunction and when used with a noun or pronoun it is called Subordinating conjunction .

e.g.: I meet my husband at the station (on is used as a preposition)

e.g.: I’ll go to the park with you (with is used as a preposition)

e.g.: She will not come unless you call her (unless is used as a conjunction)

e.g.: The poor boy went hungry until his father arrived. (until is used as a conjunction)

1) A conjunction is always followed by a verb and a preposition can be followed by a verb or noun.

2) A conjunction can be used independently in a sentence while a preposition cannot.

3) A preposition is generally used to show the relationship between certain words, phrases etc and conjunctions are mainly used to join clauses, sentences, phrases and words.

4) A preposition represents time but conjunctions do not.

5) Conjunctions are always negatable whereas Prepositions are not negatable in any case. For example: He is taller than me / I am smaller than him . Similarly, if we Reverse them then it would sound awkward. e.g. He is taller than I am, He is taller than me .

6) There are certain prepositions which cannot be used as conjunctions. E.g.: in , for , about etc..

7) There are certain conjunctions which cannot be used as prepositions. E.g.: after , before but after can be used as a conjunction.

8) For example: The man is at a very old age / The woman was very young but the woman was young is considered wrong because ‘young’ has no connection with ‘woman’ whatsoever. Therefore it can’t be used with a noun but it can be used with a conjunction e.g.: She was very young and beautiful .

Conjunctions and Prepositions both help you make sentences by connecting ideas together, but there are significant differences between these two parts of speech. A Conjunction always expresses a relationship between two words, phrases or clauses .