java vs instant coffee

java and instant coffee both are nouns.

Word	Noun	Adjective	Verb	Adverb
java	Yes	No	No	No
instant coffee	Yes	No	No	No

As nouns, instant coffee is a hyponym of java; that is, instant coffee is a word with a more specific, narrower meaning than java:

java: a beverage consisting of an infusion of ground coffee beans
instant coffee: dehydrated coffee that can be made into a drink by adding hot water

java (noun)	instant coffee (noun)
a beverage consisting of an infusion of ground coffee beans	dehydrated coffee that can be made into a drink by adding hot water