length vs physical property

length and physical property both are nouns.

Word	Noun	Adjective	Verb	Adverb
length	Yes	No	No	No
physical property	Yes	No	No	No

As nouns, physical property is a hypernym of length; that is, physical property is a word with a broader meaning than length:

length: the linear extent in space from one end to the other; the longest dimension of something that is fixed in place
physical property: any property used to characterize matter and energy and their interactions

Other hypernyms of length include dimension, fundamental measure, fundamental quantity.

length (noun)	physical property (noun)
a section of something that is long and narrow	any property used to characterize matter and energy and their interactions
the linear extent in space from one end to the other; the longest dimension of something that is fixed in place
continuance in time
the property of being the extent of something from beginning to end
size of the gap between two places