Eyelet fabrics are made by making holes on them, where each hole is sewn with a buttonhole stitch. These holes are sized and positioned precisely to create patterns, which are usually floral designs or geometric forms. On the other hand, lace is a lightweight fabric containing tiny holes embroidered and web-like patterns.  The main difference between both is that lace is more transparent, and it's often used for decoration. Eyelets, however, can be used to make entire garments. Plus, the most used fabric for lace is silk, whereas the most used one to make eyelets is cotton. Still, you can find both of these interchangeably or in the same garment.