The only way to answer the question is to generalize. There will always be individual exceptions. The pros and cons below mainly apply to engineers who only have experience in one or the other. They are personal observations and definitely do not represent _all_ engineers:
FAANG engineers
+ comfortable with thinking about scale
+ used to being on call
+ less likely to overpromise and underdeliver (consequences are worse at a FAANG)
- less able to work without requirements (they've always worked with a PM)
- used to working with incredible internal tooling
- expect a lot of compensation!
Startup engineers
+ more comfortable with switching stack/technologies
+ happier to pitch in with ideas outside of their team
+ more likely to have been involved in interviewing, even at junior level
- less used to documenting everything
- more likely to resist "formalizing" processes as the startup grows