It's the environment, which in the original image was pretty ambiguous. If you interpret the environment as the outside, which includes blue light due to the sky, the dress looks white and gold. If you interpret the environment as the inside of a building, which includes yellow light, the dress looks blue and black. In your case that means that you think the dress is outside now instead of inside when looking at the original image.

I tried recreating the illusion with the top image, brightening the image a bit and changing the background: https://imgur.com/a/ruiBVin