These needles are from DMC and the higher the size number, the smaller/finer the needle.
Size 24, 26 & 28 are slim with a blunt tip and suitable for cross stitch with size 28 being the smallest (finest) needle. Size 24 is the most common and this is what it included in most purchased cross stitch kits.
Size 16, 18 & 22 are large with a blunt tip and a large eye, suitable for tapestry or plastic canvas (or for children to use).
Size 1-5 & 5-10 are sharps and suitable for embroidery.