RC2, RC4, RC5 and RC6 were developed by Ronal Rivest from RSA Security.
In the RC family only RC4 is a stream cipher. RC4 allows a variable key length. RC2 works with 64-bit blocks and variable key lengths, RC5 has variable block sizes, key length and number of processing rounds. RC6 was designed to fix a flaw in RC5. Source: ANDRESS, Mandy, Exam Cram CISSP, Coriolis, 2001, Chapter 6: Cryptography (page 103).