The main difference is its molecular structure, which contains less silicon, and an irregular (amorphous) make-up.
Raw amorphous silicon is deposited as a thin, naturally translucent layer on a conductive glass substrate.
The aSi-PV solar panels are manufactured by vacuum depositing an ultra-thin film of the PV absorber on a conductive TCO glass surface then laminating another glass sheet on top.
The internal structure is shown in figure 1 below.