Young wine
A young wine is one that was bottled recently and is best enjoyed when consumed immediately or within one to two years of the vintage. These wines usually show their full aromas, flavors, and freshness immediately after opening. Leave the wine for much longer, they tend to “fizzle out” - losing their flavors and becoming flat and sour.
99% of the wines are meant to be drunk young.
Aged wine
on the other hand, aged wines have already spent some time, maybe a year or two, in the bottle before being released into the market. Additional aging of such wine will further soften and mellow it down, thereby improving its quality. Having said that even age-worthy wines have a technical lifecycle – some wines take lesser time to age while some others take longer.
But age alone does not say if the wine is good or bad, or if you will like it or not. Ultimately, it is a personal preference whether you like wines young and vibrant or older and mellow.