Staccato vs. Spiccato

For quite a few people it is unclear what is the difference between staccato and spiccato on string instruments. Even some sample developers aren't getting this right naming spiccato samples "staccato" and vice versa.

Both playing techniques describe short notes but have a fundamental difference in how they are created and also how they can be executed.

The main difference is the distinction between "on-the-string" bowings and "off-the-string" bowings.

With a staccato the bow never loses touch with the string which is called "on-the-string" bowing. This means there is a conscious effort to start the note by moving the bow and another conscious effort to end the note by stopping the bow movement. The note will not only stop because of the stoping of the bow movement but the contact between the bow and string will also prevent it from ringing out. Essentially, from the technical execution a staccato is a long sustained note played short.

This comes with a few consequences. The tempo at which this playing technique can be executed is limited as it is physically not possible to consciously start and stop the bow movement at very fast tempi. Also, staccato notes always have a noticeable length. In spite of them being played short, the time frame between note start and note stop will have a certain length, so if you're expecting a crunchy short note, don't expect it from this playing technique. Also, the attack on the note is not quite as instant as you might expect.

On the other hand, spiccato is a so called "off-the-string" bowing. The end of the note is not executed by stopping the movement of the bow was with staccato but by lifting the bow away from the string. Depending on speed of the passage, this technique uses either a conscious effort to lift the bow after the note is being attacked (on slower passages) which is almost like "plucking" the string with the bow, or incorporates the tension of the string and bow hair to make use of the bounce effect between the two (in faster passages). The faster the passage becomes, the more the players rely on the bounce which at very fast speeds is called "sautille".  At higher speeds the bow will touch and leave the string "in motion" which has an effect on the attack of the note which with spiccato are usually quicker than with staccato. Spiccato can be executed at any tempo but particularly shines in fast passages. While staccato always has a certain weight to the note even at low dynamics, spiccato can be executed from a feathery bouncy pianissimo to a quite agressive fortissimo. Particularly with the low string instruments and high dynamics you might even get the occasional "col legno" wood noise in between as parts of the wood of the bow might touch the string if it is executed with high pressure on the bow. 

For composers and orchestrators the distinction between the two is usually not extremely relevant and both techniques are notated with a staccato dot. The players will usually decide from the context or tempo which technique to apply. Specifying which technique to use is sometimes seen as micro management and patronizing by the  players so I would prefer using words that describe what you want to hear like "bouncy", "heavy"  or their Italian equivalents rather than requesting for "staccato" or "spiccato" as this will give the players an clearer idea of what the result should be. They might even decide to do some sort of mixed technique between the two to achieve the desired result.