Black Hat has gotten a lot bigger over the past few years, so many security insiders now compare Black Hat to the RSA Security Conference circa 2012 or so.
This is an accurate comparison from an attendance perspective but there is still a fundamental difference between the shows. In my humble opinion, RSA is an industry event, while Black Hat is more of a cybersecurity professional gathering. The focus is on cyber-adversary tactics, techniques, and procedures (TTPs), threat intelligence, and defensive playbooks. Rather than host lavish cocktail parties, vendors who participate in Black Hat must roll up their sleeves and demonstrate their technology acumen to gain street cred with this crowd.