Orandas grow their wens (the stuff on their heads) as they get older. Juvenile orandas often have no notceable wen at all.
I can't tell from your pic whether it's an oranda, fantail or telescope (does it have telescope eyes like a black moor?)
If it has telescope eyes it's a telescope. Orandas can be differentiated from fantails by the body shape, even in the absence of a wen and I think orandas have blunter faces while fantails are slighlty more pointy. Also, fancy goldfish get chubbier as they get older too, so just because yours isn't now, doesn't mean it won't be. I am assuming it is young? How big is it?