In grammar, a phrase is a group of word that functions as a single unit in the syntax of a sentence (Wikipedia). For example the house at the end of the street (example 1) is a phrase. It acts like a noun. It contains the phrase at the end of the street (example 2), a prepositional phrase which acts like an adjective. Example 2 could be replaced by white, to make the phrase the white house. Examples 1 and 2 contain the phrase the end of the street (example 3) which acts like a noun. It could be replaced by the cross-roads to give the house at the cross-roads.
Most phrases have a central word which defines the type of phrase. This word is called the head of the phrase. In English the head is often the first word of the phrase. Some phrases, however, can be headless. For example, the rich is a noun phrase composed of a determiner and an adjective, but no noun.
Phrases may be classified by the type of head they take
Prepositional phrase (PP) with a preposition as head (e.g. in love, over the rainbow). Languages that use postpositions instead have postpositional phrases instead. The two types are sometimes commonly referred to as ad positional phrases.
Noun phrase (NP) with a noun as head (e.g. the black cat, a cat on the mat)
Verb phrase (VP) with a verb as head (e.g. eat cheese, jump up and down)
Adjectival phrase with an adjective as head (e.g. full of toys)
Adverbial phrase with adverb as head (e.g. very carefully)
Clauses are the principal structure of which sentences are composed. A sentence may consist of one, or more than one clause. Clauses mean also group of words that contains a subject and a verb (Oxford Learner’s Pocket Dictionary, 2005: 72)
A clause can be analyzed into five different types of clause element: Subject (S), Verb (V), Complement (C), Object (O), and Adverbial (A), For example:
Figure 1. clause constructions
The largest unit of syntactic analysis is the sentence (S). Sentences are units made up of one or more clause (leech and Svartvik, 1979:288). Sentences containing just one clause are called ‘Simple’, and sentences containing more than one clause are called ‘Complex’.
Figure . Sample of the structure of S (traditional view of a sentence)
Leech.G. and Svarth Jan. 1975. A communicative Grammar of English. Longman Group Limited. London.