significant vs substantial

significant and substantial both are adjectives.

Word	Noun	Adjective	Verb	Adverb
significant	No	Yes	No	No
substantial	No	Yes	No	No

As adjectives, significant and substantial are synonyms defined as:

significant (adjective)	substantial (adjective)
important in effect or meaning	having substance or capable of being treated as fact; not imaginary
too closely correlated to be attributed to chance and therefore indicating a systematic relation	of considerable importance, size, or worth
of considerable importance, size, or worth	of or relating to the real nature or essential elements of something
rich in significance or implication	having an abundant supply of money or possessions of value
	of good quality and condition; solidly built
	providing abundant nourishment