In spinning fiber one can use different techniques to draft while spinning. There is a difference in the resulting yarn resulting from the technique used.
In short;
With a short draw technique the yarn will look very controlled, sleek and tidy and usually is more dense and heavy.
With a long draw technique the yarn ends up being more fluffy, light and lofty which creates a light and airy yarn that could trap more air and be more warm in for instance a jersey.
I have until recently only spun using the short draw technique. But am experimenting with and starting to enjoy and appreciate the long draw technique and resulting yarn.
My big Grace Wheel I have found to be ultimately suitable for the longdraw, with its relaxed action and big fly wheel. So I am using her more again. Also because I can finally, finally with this technique easier produce thicker yarn again. Yippee!!!
This photo shows the quality of the long draw spun yarn well, I think.