Birch Polypore in Stoke Woods?

Birch Polypore in Stoke Woods?

Observation - Birch Polypore in Stoke Woods?. Description: I think these are Birch Polypore but the top sides of the brackets vary in colour and shape, so I'm not sure whether there's actually more than one variety here or whether it's just down to differing lifecycle stages. I'm sorry the pictures aren't cleare

I think these are Birch Polypore but the top sides of the brackets vary in colour and shape, so I'm not sure whether there's actually more than one variety here or whether it's just down to differing lifecycle stages. I'm sorry the pictures aren't clearer but I couldn't get closer to the tree without damaging a lot of undergrowth.