Interfacing is a material that’s used to add body and rigidity to another fabric, by stitching it in between two fabrics. Unlike interfacing, stabilizer is created to be removed after stitching. Stabilizer helps reinforce fabric when stitching may damage it.
Fusible fabric is a fiber that is used to fuse two fabrics together by placing between two pieces of fabric and heating. It is not woven or knitted. It’s often used to make fabrics stiffer and for mending hems and small holes.