A colleague had been discussing the difference between such as X and such X as with some friends, and asked for further insight from the rest of us. I gladly weighed in:
The first thing to note is that it’s actually a choice between X such as Y and such X as Y. But those two constructions are not the same thing, though they can mean similar things.
The X such as Y is more often said X like Y and focuses clearly on the X:
Cakes such as this one are expensive.
I’ve been talking to people such as my barber.
In both cases, we’re adding a modifier that is effectively a prepositional phrase, “such as this one” and “such as my barber,” to modify the noun (“cakes,” “people”) as an adjective would. The head noun is an unspecified class – it starts with all cakes or all people and then imposes a limit.
In the such X as Y case, on the other hand, we start by specifying the class – the implication is already that there is a subset of the class that is focused on. But there’s more to it than that. Do these sound right?
Such cakes as this one are expensive.
I’ve been talking to such people as my barber.
The cakes one might be OK; the barber one doesn’t work, really, does it? Are you expecting something more? Try:
I’ve been talking to people such as my barber might know.
Here are similar cases that will work:
Such ducks as you may see on the river are typically overweight.
Such cakes as come out of this bakery are expensive.
Aha! The Y in these cases should be a verb phrase; the “as” is a subordinating conjunction. The true structure of it is two parts: first, “such X” – a structure that can stand by itself (“People don’t do such things!”) – and then “as Y,” a relative clause.
However, there is still the case of such X as Y where the Y is not a clause, as in the cakes example or, even better (thanks to Aaron Dalton for this example), this one:
I have been to such countries as France and Italy.
This is still a such X with as Y modifying it, rather than an X such as Y, but it’s not subordinating a clause. The “as” is like “like” here. The key difference between “countries such as France and Italy” and “such countries as France and Italy” is that the second instance presents the generic “countries” as already specified into a subset. It’s not simply that France and Italy are examples of countries I’ve been to; it’s that they’re examples of the sort of countries I’ve been to.
In short, X such as Y is a single construction presenting instances from a generic type, while such X as Y is a two-part construction presenting examples of a subset, or presenting a subset with a further qualifying clause.