As you can see, in sentence 1 the words are past participles (the elephants have been outjeweled) whereas in sentence 2 the words are gerunds (the elephants are beingjeweled). These different parts of speech correspond to different word types: verbs (past participles), adjectives (amplifiers or adjectives), nouns (generic nouns which may or may not have a determiner, as in the two examples above) and noun phrases (compound nouns).
Most of the time it is not necessary for us to make a distinction between these various types of word, yet knowing the names of the different word types is useful. For example, once we know that ``centipedes'' is a noun phrase containing a generic noun and an adjective, it is much easier to see why that noun in that sentence is a housefly - usually called a fly - and not an elephant.
Brief introduction to some of the more common word types. There is no generic word ``participle'' in English, though some grammars give this label to another word type which is a verb in the past participle. In English, an adjective which occurs in a noun phrase is called aadjunct of that noun. Therefore, a book is an adjunct of a book is a book. Adjectives which are predicative (that is, they can be the head of a noun phrase) are known in English as adjectival complements.
The word ``noun'' does not mean just the head of a noun phrase, but the word can be used synonymously for noun phrase. Nouns when they take an adjective as their head are called attributive adjectives. Likewise, a noun can act as a head for a predicate (also called an attributive predicate or adjectival predicate). d2c66b5586