There's also usually a switch from ISO to NSO somewhere down the line, often fairly early. NSOs aren't capped at a 90 day post-termination exercise window. Some companies have extended the window to as much as 7 years - Pinterest comes to mind. There is a cap, but it's closer to the RSU cap than the ISO cap.

The progression is usually:

- Founders get shares with a re-purchase option for vesting. The company exercises the option if you leave before vesting ends to take back your un-vested shares.

- Next ~100 people get ISOs.

- Next ~2000 get NSOs.

- Then, double-trigger RSUs until the company goes public.

- Then, single-trigger RSUs.

I agree with your general assessment. The difference between options and RSUs usually comes down to upside potential. An option is worthless at grant time (by law, it usually has to be issued at the 409(a)) and it's just the right to buy company shares. If you're buying the shares at the current price, there's no value in that. Options only gain intrinsic value of future appreciation in the underlying equity past your grant date.

On the other hand RSUs are shares of the company, so they are worth at grant whatever a share of the company is worth.

An option with a $10 strike price to buy shares of a company whose 409(a) is $11 has an intrinsic value of $1. An RSU of a company whose 409(a) is $11 has an intrinsic value of $11.

Companies generally, in my experience, give you about 3X as many options as they would shares for the same role. Give or take. Companies usually switch from options to RSUs when they think that growth in the stock price is going to slow down - [edit] (and when they're hiring people with a higher aversion to risk!)