yellow face type 1 means it only stays in the face, type 2 means the yellow spreads throughout the body For example, Julio is a yellow face type 2, his head and wings are yellow, and it makes the grey on his chest look more like a stormy blue. If he was a type 1, only his face would be yellow, his wings would be white, and his grey would be more rich and darker (I wonder what he would actually look like? )
Here is an example of yf type I and II :
This is one of my hens, Daisy, when she was young. She looks like a yf type I because the yellow is only on her head, and hasn't seeped into her body feathers.
This is her now after her first moult. This photo doesn't really show it, but her feather were just getting their green tinge to them. She is much more green now.
You can also see how the main colour in her wings are yellow. This is because she is a double factor spangle. If she was a single factor spangle, the main colour would be white, but because yf has seeped into her wings as well, she is double factor. So over all, Daisy is a yellowface type II double factor grey spangle.
Hope this helps,