Different currencies can separate different decisions. A general resource may support everyday progress, while another is tied to a particular mode, event or purchase. The icon alone does not tell you whether two balances are interchangeable.
What the distinction means
For a player, the practical issue is opportunity cost. Spending a resource on one goal can remove the option to use it elsewhere, while an event-specific balance may have its own expiry or conversion rule.
What to consider before playing
Read the description of the exact currency before treating it as equivalent to a more familiar one. Ask where it is earned, where it is spent and what happens when the relevant activity ends. A reward with a large number can be less useful than a smaller reward in a resource you actually need.
The useful takeaway
Different currencies can separate different decisions. Read the description of the exact currency before treating it as equivalent to a more familiar one.