What is the difference between relevance and admissibility?

Answer 1

There is no real difference, except that relevance is the right word. Relevancy's extra syllable is an unnecessary addition that brings no new meaning to the word.

However, according to Merriam-Webster, relevancy came into use in the 1500s and relevance came into use in the 1700s.

Answer 2

Admissibility refers to whether or not certain evidence could be admissible in court, at trial. Evidence is subject to a variety of rules in order to be admissible. Relevance refers to whether or not the evidence matters. That the evidence be relevant is one of the requirements of admissibility.

Answer 3

Suppose you were studying soybean plants and found that there is a strong correlation between plant height in mid-August and bean weight at the end of September. I would say that this would come as little surprise to a farmer because it would simply confirm their suspicion that healthy plants produce best. In this situation bean production is relevant to a farmer's concerns but the health of the plants is relevant only insofar as it makes for good bean production. Much more relevant would be the underlying conditions which would have given rise to the differences between the productive powers of the plants.