Hi A -would suggest that as granulated sugar is the result of boiled sugar juice - cane or from beet - the suppliers have switched hence the difference.
The crystals form as a result of processing the juice once it has been treated - often with lime wash to obtain the white colour and some producers in the US use bone char - which is burnt (largely pork) bones, used as a filter to remove impurites.
The processing also can use phosphoric acid, calcium hydroxide and carbon dioxide, varioous degrees of filtration (hence the bone char) maybe through carbon filters, then the grade of granule is reached.
The sugar market is pretty big worldwide, and if you notice a change in the contents of the bags, there are quite a few factors which will affect tthe final product. So - do you actually need sugar then.......?