Just make like the image, you will be abe to walk at the staircase made with snow only(4 levels to make a slab and 8 levels to make the full block), but if use a block (even snow block) instead of the 8 levels of snow, you won't be able
Description from MC-8781:
Any block consisting of the new layered snow sheets will have a hitbox that is 0.125 lower than the what block looks like it should be. A full block made of layered snow sheets will be 0.875 tall, whereas an actual snow block is 1 tall (despite the fact that they look exactly the same)
