Most people are able to tell the difference between a saxophone and a clarinet (save for those rare individuals who call a Soprano Saxophone a metal clarinet or a Bass Clarinet a wooden saxophone), but the number of people who confuse bassoons and oboes is strikingly high. Perhaps this is because the oboe family doesn’t descend into the bass register or the bassoon family ascend into the soprano. Yet, the two instruments are fundamentally different.
The reed of an oboe and the reed of a bassoon, despite both being double reeds, are very different than one another. This is unlike the clarinets and saxophones who can use each others reeds (Alto Clarinet can use Alto Saxophone reeds, Bass Clarinet can use Tenor Saxophone Reeds, etc.). Bassoon and oboe reeds are nothing like one another. Were we to have an oboe and bassoon of the same pitch (the only time this occurs is on the Bass Oboe and the Alto Bassoon) the reeds of those instruments cannot be used on one another.
The first difference is the staple on oboe reeds. A staple is a metal tube to which the cane is tied. All oboes have this. Bassoons do not. The bassoon reed is made of cane alone (save for the string and wire that holds the two halves together), and the cane goes directly onto the instrument (onto the bocal).
The second difference is how the cane is scraped. The scrape of the bassoon reed is fairly simple tapering from the back to the front and from the center to the sides. Oboe reeds are much more complex. To best illustrate this, have a look at this diagram. Here, I’ve drawn the basic “American” scrapes used in this country. Other countries and styles will use slightly different scrapes.
You can see how much more complex the oboe reed is. There are some similarities like the spine and the tip, but these features are also present in single reeds. You can also see that the shape of the reeds are very different. Oboe reeds are much straighter while bassoon reeds have a wide flare.
Next is the bore shape. While both have a conical bore, the cone of the oboe and the cone of the bassoon are very different. The oboe’s taper is quite wide. Were it to start of as wide as the saxophone, it would have a taper close to the saxophone family. The reed here is the limiting factor. Conversely, the bassoon starts off at roughly the same point as the oboe, but over its length, which is four times as long as the oboe, the bell is only slightly bigger than the oboe. Therefore, the taper of the bassoon is much smaller than that of the oboe. In fact, the bassoon has the smallest taper of any instrument.
Lastly, the key systems. First different is that the bassoon family’s fundamental key is F while the oboe’s is C. All bassoons have a fundamental extension a perfect fifth below their 7-finger note, while oboes one have an extension of a second (major or minor depending on the size).
Aside from the aspects that are fundamental to all woodwind key systems, the actual keywork of the bassoon and oboe are completely different. In fact, the oboe’s keywork is nearly the same as that of the saxophone. There is no instrument who shares the bassoon’s odd melange of fingerings.