NEMA symbols are for electrical drawings, not electronics, so there would be no differentiation between types of capacitors, it’s just a capacitor, and in electrical drawings, usually Power Factor Correction caps or motor starting caps are the only ones we see.That's a great find.
Maybe @Dennis Alwon will add it to his Resources directory.
On the first entry, what they call NEMA capacitor symbol is what the electronics industry uses for Electrolytic Capacitor.
What they call IEC capacitor is what we use for Ceramic Chip Capacitor, so at times we see both symbols on a plan.
Specifically, Texas Instruments does it this way and it makes it easy to see an application design to know what's involved without digging up the part numbers and looking up the parts.
For me, I prefer to avoid the electrolytic caps due to their history of failure (think Dell computer motherboards in the 1990's and forward).
With today's modern buck converters we can buck 24VDC down to 3.3VDC with only ceramic chip caps and an inductor, with very low ripple and nearly 90% efficiency.
The concept of a legend sheet is our standard here, because we don’t always adhere to any national standards for drawing symbols. But elsewhere in the world that uses IEC standards, they are rigidly specific, so they don’t use a legend sheet because they expect anyone qualified to work on it to be well versed in IEC symbology. Unfortunately they don’t care that people here are generally NOT trained on or even exposed to IEC symbology.