I have seen Curve25519 and X25519, Curve448 and X448. I've seen a small note in this answer
(Historical note: Originally, X25519 was called Curve25519, but now Curve25519 just means the elliptic curve and X25519 means the cryptosystem.)
- Is it a standard to say CurveABC is the Elliptic Curve and XABC is the cryptosystem?
- Or, it is just a convention between the Elliptic Curve Cryptographers.