These are part of the core meaning of the sentence, but if omitted still leave a meaningful sentence.

:John and Sophia helped me with my homework.

Conjuncts: These link two sentences together.

:John helped; therefore, I was able to do my homework.

Disjuncts: These make comments on the meaning of the rest of the sentence.

:Surprisingly, he passed all of his exams.

Distinguishing an adverbial from an adjunct