There's some confusion about what schnapps is, what cordials are,
and what liqueurs are. This situation is exascerbated by some
benign misuse in the commercial alcohol market, as well as regional
interpretations that can be quite different. So while I can offer
some technical definitions, don't go complaining to your local liquor
store that some bottle or other is mislabeled...
For years I labored under the mistaken impression that "schnapps" was just another synonym for "liqueur." Indeed, more than once I've been asked what the technical difference between a schnapps and a liqueur really was, and not only could I not say, I couldn't find any books that could say, either. Finally, someone came along and gave me the real story. Many thanks to Albert Grimm for setting me straight.
In his own words, Schnapps, a German word, "is the generic term for all white (clear) brandies distilled from fermented fruits. True Schnapps has no sugar added and is definitely an aquired taste, particularly for nationalities not used to raw distillates." So schnappses are different from liqueurs on two major fronts, they being both fermented and distilled, where liqueurs are simply fruits steeped in an alcohol which has already been fermented and distilled. You will also hear the words eau de vie in the context of liqueurs. I believe (though I'm always happy to be corrected) that this is a French expression for an unsweetened fruit brandy, very similar in nature to Schnapps. It has come to be used to mean an unsweetened liqueur as well, probably because of the similarity of taste and texture. But the original meaning was most likely as a brandy. Anyway, most significantly, this means that the run-of-the-mill home liqueur maker will never be able to really capture the whole essence of many commercial schnappses. The chemistry just isn't there.
Now, this doesn't mean that you should throw your hands up and walk away from ever trying to make a decent copy of a true schnapps. Liqueurs do go a long way towards tasting like real schnapps, and can make some compelling tastes on their own. One of my original intents in making liqueurs was to copy peach schnapps. I can't make it perfect, but a simple peach liqueur with some strategic addition of glycerine can fool all but the most discriminating palates.
It's worth noting that true German schnapps is not what we get in
United States. The major American commercial brands are all heavily
and have added glycerine as well. It's about as close to true German
perhaps as American beer is to its German counterparts. If you want to
try to capture the taste of a true schnapps, consider making an eau
de vie. Basically, make your liqueur, but ignore the requirements
sugar. Whether to add the extra water without sugar is your own choice.
I recommend experimentation, as always.
Cordial, on the other hand, has a different meaning depending on
where you say it. In the US, it almost always means a syrupy,
sweet alcoholic beverage. In fact, in the US, "liqueur,"
"schnapps" and "cordial" all occupy that nebulous field of flavored
hard liquor, with varying degrees of sweetness. In many other
parts of the world, most commonly the British Commonwealth and her
former possessions, cordial actually means a non-alcoholic,
sweet, syrupy drink. One of the most well-known commercial
cordials, Cadbury-Schweppes' Rose's
Lime Cordial, is a good example of this confusion.
Originating in London, Rose's Lime has always been called "cordial"
among the English. But in North America, it's called Rose's Lime
Juice because consumers, upon reading "cordial," would immediately
Unfortunately, we Americans all drink soda (I mean tonic - I mean
pop), so there seems to be very little domestic market for the things
the British would call a cordial, except as cocktail mixers. So
if you're looking for recipes for UK-style, non-alcoholic cordials, I
definitely don't have any, but I can't even suggest what a better term
to look for them would be.