Ball Point needles are specifically designed to be used with knit and stretch fabrics. They have a rounded point rather than a sharp one (the larger the size of the needle, the more rounded the needle point) and they push between the fabric yarns rather than piercing them the way the Sharp Points do. The needles should be used when sewing with interlock knits, coarse knits and other fabrics that will run if snagged. The needles come in varying sizes from 9 to 16. The larger the size of the needle, the more rounded the needle point is.
Sharp points (regular) are for use with woven fabrics (including cotton and linen etc) because they cause a minimum amount of puckering and produce an even stitch without damaging the fabric. These are not recommended for use with knits as they can cause skipped stitches. Sharp points are more slender through the shaft and should be used when edge stitching on woven fabrics, sewing on finely woven fabrics or heirloom stitching on very fine fabrics. They are also a good choice when sewing with synthetic suede. These needles come in varying sizes from the finest size 9 to the heaviest size 18