The single slit diffraction pattern is based upon the width of the slit, while the double slit interference pattern is based upon the spacing between the slits.

The diffraction of light at the single slit can be explained by the Heisenberg uncertainty principle. The more the light path is narrowed, the wider the diffraction pattern of the slit appears on ...

This interference pattern appears in the shape of the orientation of the struts; these are the diffraction spikes we see.