In my experience, I feel they are pretty different.
I had a semester of foil in college, so I cannot speak for the epee nor saber used in western fencing. My Chinese sword practice is mostly Chen and Yang tai chi, altho I have a bit of external wudang sword as well, and a two-handed straight sword set.
The foil is all about stabbing, while the jian has a workable edge as well as a sharp point. Sure, there are some occasional similarities, but overall I'd say they are quite different. Stances are very different, footwork is very different, defensive postures are mostly different. Jian has a larger body of techniques with more variation than foil.
If you look hard enough, you can always find similarities. But overall I feel they are not very similar.
The foil is such a modern version of "fencing" that it is hard to use that as a comparison to a lethal Chinese alternative. As far as I know, there is no Chinese version of a foil. (The foil was based on "smallsword" techniques -- not rapier or side-sword.)
The hard part about this question is that there are many, many different styles of historical fencing, plus the modern counterparts of foil, epee, and saber. But the kicker is that for each style, either the style was built around the limitations of the weapon, and the quality of steel which limited its size and weight, or the sword was built around the style later, when metallurgy allowed that.
The "Rapier" changed a lot over time, from the cut-and-thrust broadsword (Almost a Oakeshott type XV with a knuckleguard attached) at one end of the spectrum (Similar to what you would see from Marozzo), to the 4-foot long monstrosities you would sometimes see the in the Spanish styles, to the short, flimsy smallswords, to the point-only epees used for "first blood" duels.
Marozzo, Thibault, Saviolo, Silver, Fabris, Agrippa, Capoferro, Alfieri, di Grassi, Carranza, Distreza, and Narvaez, are just some of the distinct fencing styles out there. (Most of them are named after their designer) Not to mention the older long-sword styles, and the newer foil, saber, and epee. Odds are pretty good that at least one of them used a sword similar to the Chinese, and therefore would have used it in a similar way as the Chinese.
I am not familiar enough with the Chinese Sword to point you in the right direction, though, as far as which one.
Hope this helps.