The most appealing feature of drop spindles is the portability. If you want to be able to walk around outside as you spin like the Inca have for centuries, use a low-whorl spindle.
Spindles are an ancient tool used around the world in a variety of cultures for spindle spinning a variety of fibers.
It's amazing that all fabric began this way for thousands of years. Every bit of cloth started with someone spinning it into yarn or thread by hand using a spindle.
We tend to take things like cloth for granted now that we have machinery to make the process faster.
Think about it: Famous historical figures like Cleopatra, Jesus, Charlemagne, and even Columbus all wore clothing that began handspun on a spindle.
The two types function the same way by twisting the fiber into yarn. The difference is in how they are operated.
There are also some variations in drop spindle types depending on where the whorl is placed.
They all basically consist of a shaft with a round whorl to add weight and a notch or small hook at the top to guide the yarn.
Some suspended spindles can also be used as supported spindles. This type has a point on the bottom that can rest against a surface to release some of the weight.
You can make your own spindle and recycle old CD discs using this .pdf pattern from Worldinaspin.
Note that this pattern says to put the CD whorl near the top, but beginners will have an easier time if you put it near the bottom. That makes the spindle more stable and easy to balance.
You need to learn to manage the weight and momentum so that the fibers spin the way you want them to go and at a steady speed.
With some practice, spindle spinning can be done with one hand, so you can easily take it with you while you go for walks or do other tasks!
Spindles are still as fast as or faster than a wheel for spinning strong, fine yarns, but they require more training and skill. Spinning wheels can produce good results with less study in form and technique, so they became popular as a way to use cheaper unskilled labor.
To study spindle spinning is to study world cultures. I would love to learn more about the different types and the places they come from!