synaesthesia vs sensation

synaesthesia and sensation both are nouns.

Word	Noun	Adjective	Verb	Adverb
synaesthesia	Yes	No	No	No
sensation	Yes	No	No	No

As nouns, sensation is a hypernym of synaesthesia; that is, sensation is a word with a broader meaning than synaesthesia:

synaesthesia: a sensation that normally occurs in one sense modality occurs when another modality is stimulated
sensation: an unelaborated elementary awareness of stimulation

Other hypernyms of synaesthesia include aesthesis, esthesis, sense datum, sense experience, sense impression.

synaesthesia (noun)	sensation (noun)
a sensation that normally occurs in one sense modality occurs when another modality is stimulated	an unelaborated elementary awareness of stimulation
	the faculty through which the external world is apprehended
	a general feeling of excitement and heightened interest
	someone who is dazzlingly skilled in any field
	a state of widespread public excitement and interest