They look similar, but they do have their differences as you can see. The flanges are different thicknesses and the piping thickness is different as well. 12mm flanges front and rear for Tomei and 12mm front and 10mm rear for SSI. Pipe thickness is 1.5mm for Tomei (same as stock) and SSI has a thickness of 1.8mm. Other than that, they seem very similar. Runner diameter is the same (42.7mm) as well as the collector (60.3mm SSI and 60.5mm Tomei).
