What's the difference in these achievements?

[Claytonic]

What's the difference between the achievements "Metal Sonic" and "The Perfect Adventurer"? They both say "get all 130 emblems" (Metal Sonic adds "by playing Sonic Adventure DX"), but they have different % of players getting them? How can you get one and not the other?

[OSA413]

Afair you unlock The Perfect Adventurer achivement after you collect 130 emblems, Metal Sonic achievement unlocks after you go to the Trial mode and see Metal Sonic in the Character select.