Noun clause and adverb clause differ in few ways:
1. Function in sentences
1.1. Function of noun clause
Noun clause is a dependent clause that functions as noun in a sentence. Since it functions as noun, it can occupy nominal positions such as subject, direct object, object of preposition, and subject complement. (It rarely functions as indirect object or object complement.) Examples:
Whether she will recover from the illness is uncertain. [Subject]
She wondered whom she would invite to the party. [Direct object]
They discussed the reasons behind why the plan failed. [Object of preposition]
The question is which option we should choose. [Subject complement]
Being a subject, object, or complement, a noun clause is an essential part of a sentence: Dropping it will result in a non-grammatical sentence. The sentences we just saw will look like these if we drop the noun clause:
is uncertain.
She wondered. [She wondered what? Without an object, it’s not a sentence.]
They discussed the reasons behind.
The question is.
1.2. Function of adverb clause
Adverb clause is a dependent clause that functions as an adverb in a sentence. Being an adverbial, it answers variety of questions (time, place, manner, degree, reason, result, preference, exception, similarity, comparison, contrast, concession, condition, and more), providing background information in a sentence. You can also say it expresses variety of relationships. Examples:
The team finished their presentation before the clients arrived from their overseas trip. [Time: The adverb clause gives information on time.]
Wherever there is an opportunity to learn, she eagerly takes it on to expand her knowledge and skills. [Place]
He prefers reading fiction for relaxation, while she enjoys non-fiction for learning. [Contrast]
She received a scholarship because her academic performance was outstanding. [Reason]
She completed the marathon, even though she was injured halfway through. [Concession]
But for few exceptions, adverb clause can occupy more than one position in a sentence. Some of the above sentences, for example, can be written as:
Before the clients arrived from their overseas trip, the team finished their presentation.
While she enjoys non-fiction for learning, he prefers reading fiction for relaxation.
Because her academic performance was outstanding, she received a scholarship.
Being a modifier (adverb), adverb clause is not an essential part of a sentence: Dropping it will result in a grammatical, though less informative, sentence:
The team finished their presentation.
She eagerly takes it on to expand her knowledge and skills.
He prefers reading fiction for relaxation.
She received a scholarship.
She completed the marathon.
2. Marker words
If you noticed in the earlier examples, the two dependent clauses have been introduced by words such as whether, whom, why, which, before, wherever, while, because, and even though. They’re called marker or trigger words. They mark the beginning (or they introduce) the two dependent clauses.
Marker words work differently in the two clauses.
2.1. The two clauses have different set of marker words, many of which overlap.
Noun clauses are introduced by marker words that, if, whether, who, whom, whose, what, which, when, where, why, and how. Out of these, that can sometimes be dropped when the clause functions as direct object of verb. Example:
It’s clear (that) they need more time. [You can retain or drop that.]
Adverb clauses are introduced by a much longer list of marker words, with the common ones being because, as, since, before, after, until, unless, while, whereas, though, although, even though, if, when, as long as, as soon as, like, where, so that, and such that. None of them can be dropped.
The two clauses have few common marker words: when, where, if, and whether. Here are few examples for you to understand how they introduce two different clauses. Where the clause is noun, you can drop it and still have a meaningful sentence, or you can replace it by a noun phrase. Where the clause is adverb, it can usually be moved to front or back. Where the clause is adverb, it provides variety of background information (or expresses variety of relationships) such as time, place, manner, degree, reason, result, contrast, and condition.
When
Do you know when she’ll be arriving? [Noun clause as direct object. Dropping it will result in an ungrammatical sentence. Alternatively, you would be able to replace it by a noun phrase and get a meaningful sentence: Do you know the arrival time?]
Time flies quickly when you’re having fun. [Adverb clause providing information on time. The adverb clause can be shifted to front as well.]
Where
I can’t remember where I left my keys. [Noun clause as direct object]
They decided to camp where the river bends. [Adverb clause]
If
We need to check if the package has been delivered. [Noun clause as direct object]
I will call you if I need help. [Adverb clause]
Whether
Whether she will recover from the illness is uncertain. [Noun clause as subject]
Whether he comes with me or not, I’m going for a walk. [Adverb clause]
2.2. Marker words are different part of speech in the two clauses.
In a noun clause, marker words who, whom, whose, what, which, when, where, why, and how can be pronoun, determiner, or adverb. (Specifically, they’re called interrogative pronoun, interrogative determiner, and interrogative adverb.) Marker words that, if, and whether though are treated as subordinating conjunction. Examples:
I don’t know which is the best route to take. [Which as pronoun]
The question is which option we should choose. [Which as determiner]
They discussed the reasons behind why the plan failed. [Why as adverb]
Whether she will recover from the illness is uncertain. [Whether as subordinating conjunction]
In an adverb clause, marker words are subordinating conjunction.
In this post, we looked at the difference between noun clause and adverb clause. For difference between other dependent clauses, refer to:
