"Length"-output in DNSSEC-Policy state-files vs. "Key Length"-output on dnsviz.net

[Tom]

Hi list

Using BIND-9.16.27:
I'm wondering about the value of the "Length"-field in the dnssec-policy 
state-file output, which results in "Length: 256" for domains, which are 
signed with algorithm 13 (ECDSAP256SHA256) and the "Key length"-output 
for the domain on "dnsviz.net" (ZSK or KSK), which results in "Key 
Length: 512".


# state file
$ grep Length Karcademics.ch.+013+19238.state
Length: 256

# The ZSK/KSK for this domain on "dnsviz.net"
Key Length: 512

What's the difference between this both values?

Many thanks.
Tom