Deep structure:
Represents the underlying meaning and grammatical structure of a sentence, before any transformations are applied. Phrase structure rules are designed to capture this underlying structure by specifying how phrases can be combined to form sentences.
Surface structure:
This is the actual form of the sentence that we hear or read, which is derived from the deep structure through various transformations.
Kernel sentence:
While related to deep structure, a kernel sentence is a simple, declarative sentence with no transformations applied, considered the core structure from which other sentences are derived.
