Do I have dandruff or dry scalp?

I really am not sure whether I've got dandruff or just dry scalp. For years now I've had little white flakes falling from my hair eveytime I touch it. (There's a lot of them by the way ). It isn't itchy.

How can I know what it is?
Updates
+1 y
PS: Most of it goes away if I wash my hair in the morning (no soap, just water) but next day it's there again. Same effect if I put olive oil in my hair (lasts for one day)
Updates
+1 y
Oh, and I almost never wash my hair with soap or shampoo. I just use water.
Do I have dandruff or dry scalp?
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