But then you are assuming they are different. You are assuming there is no baseline, you are making assumption either way.
It's either they are the same or they are different, it's one way or the other. I too want to assume they are different like you, but as I keep saying I don't want people to think "Oh you just don't want to have Fate verse be weak because of bias" when I am comparing Danmachi to Fate.
Though I feel more safe to assume they are different, now knowing you guys assume they are different too.
No, I'm saying they are different because they have different feats. Adamantite in Danmachi breaks under attacks that are city or less in intensity. Adamant in Fate has taken planet level attacks without breaking.
For the record they don't even share a name, much less any specific characteristics. The metal in Danmachi is called Adamantite, while the one in Fate is just called Adamant. Because it's named after the Adamas Scythe Chronos weilded, iirc.