What is meant by "KDF2" vs "PBKDF2"? I see many references to KDF2 here, but all links are broken and Wikipedia does not have an entry for KDF2.  Is KDF2 a specific standard for Key Derivation without a password?

Ultimately, I am trying to make sense of why KDF2 is listed as PRNG for Crypto++ on Wikipedia.
KDF2 is a KDF defined in ISO 18033.  You can find a draft of that spec here.  See section 6.2.3.

As to why it's listed as a PRNG, remember that a KDF relies on a pseudo random function (PRF), so it's output needs to be random.