I noticed a sale of "vintage LEGO" at the marketplace I follow to find new items to my collection and keep up with the price trends. To my shock the seller wss offering sets from the 90's! Not quite vintage to me.
While the term vintage isn't strictly defined it is usually used for items more than 40 years old. I personally consider items made before I was born as vintage. So I would call those sets retro at best even though for me personally they were already too new even for that.
As with vintage, retro doesn't have strict definition either. Usually it's considered to be items between 20 and 40 years old. But this can be highly personal as well. Retro items are those that remind you of your past, they have some nostalgic value in addition of just being (relatively) old.
Vintage doesn't either go all the way back to the beginning of time. Items over 100 years old are antique. But even that doesn't go too far back in time. Not even back to the antiques times. Anything older than 300 years are already considered artefacts.