Adjuncts are grammatically required by the verb, while complements are entirely optional.

Complements are grammatically required to complete the verb's meaning, while adjuncts are optional additions.

Complements are highly mobile and can change positions, while adjuncts have a strictly fixed position.

Complements modify nouns, while adjuncts modify full verb phrases.

Specifiers

Parenthetical elements

Connectives

Adjuncts

Ed-clause

Finite Adverbial Clause

Ing-clause

Verbless Adverbial Clause

It converts the statement into a formal, interactional speech act.

It splits the clause into "given" and "new" relative structures.

It triggers mandatory subject-auxiliary inversion.

It provides a temporal anchor for the narrative immediately.

The traffic is heavy; they must be late.

He can speak three languages fluently.

Students must submit their papers by Friday.

Charles may be at home now.

Single complementation

Complex transitive dual complementation

Transitive-oblique single complementation

Ditransitive dual complementation

Only at the very beginning of the sentence

At the end of the sentence

Always between the subject and the verb

Immediately before the direct object

whether

that

if

why

Notional subjects

Dummy subjects

Substantivized subjects

Peripheral subjects

Relative clauses are never preceded by commas, while adverbial clauses always require them.

Adverbial clauses can be non-finite, whereas relative clauses must always contain a tensed verb.

Adverbial clauses must always use "wherever," while relative clauses use "where"

Adverbial clauses modify a verb and have no noun preceding them, while relative clauses modify a preceding head noun.