How can the second guy, Eugene Wu, possibly be a professor straight after getting his PhD? That's insane! In the UK you'd have to do probably 20 years after your PhD as a postdoc and then lecturer before you could remotely hope to get a chair. How come he's gotten it immediately?
Yeah, it's quite common in the US in CS. I think you may also be confused because "professor" in the US is still used even for the lowest-ranked tenure-track positions (and even for adjuncts).
Assistant professor is the entry-level academic position in the US.
Many people do a postdoc first, but it's not uncommon to go straight to assistant professor right after getting your Ph.D., especially if you came out of a renowned school like MIT.
eugene is just THAT good. and also in the U.S., the first tenure-track position after a Ph.D. is called "assistant professor", which differs from terminology used in other countries.
If you are a top grad at a top program in CS, there tends to be enough faculty spots. Some day far in the future when funding dries up and the field gets older, I assume there will be fewer open spots vs. recent PhDs, so more and more grads will have to do extended postdocs to prove themselves worthy of a faculty position.
There are various higher positions like head of department/faculty and prestigious professorships, e.g. the Lucasian Chair in Cambridge.
Lecturer is normally the first 'tenure track' job people get after being a postdoc for a few years. It's the first of the permanent placements you can get. That said, postdoc is a catch-all and doesn't necessarily mean fresh grad. There are postdocs in my group who are nearing retirement and have stable jobs.
Great read. Thanks again @pgbovine!