>what differences do you see?

In big corp's non-producing types are basically trying to get VPs to give them more power and money. In startups, founders are trying to get investors to give them more power and money. In both cases, engineers are simply seen as tools to achieve these ends.

Start-ups have only one power structure whereas big corps have lots of feudalism going on. At a start-up, the only recourse an engineer has against the bureaucracy is to quit. At a big corp there's more options.

At start-ups, douche-ey behavior can get out of hand. There's not the normalizing force of a large corp to keep people's egos in check.

There are exactly zero pros to being an employee other than it prevents homelessness. If you're an engineer working as an employee, forget about trying to find a better job. They don't exist for engineers. My advice is to do what I'm doing. Have your quit date planned and focus on that and nothing else.