Boro and sashiko are two terms that are often mentioned together, but they don't really mean the same thing.
Sashiko is the technique itself – the small stitches that are sewn in patterns across the fabric.
Boro is instead a way of describing old Japanese textiles that have been repaired and reinforced over and over again over a long period of time. These garments often consist of many layers of fabric sewn together with sashiko stitches.
The result is textiles where repairs, patches and stitches together form a unique pattern.
Today, the word boro is often used to describe the special aesthetic that arises when textiles are visibly repaired and reinforced.