1. You get $X of stock grant when you join. This gets converted to number of stocks based on the value of the stock when you join and then the stock vests over the next 4 years. So if you get a stock grant of $400k when you join and the price of the stock at joining is $1000, you get 400 stocks that vest over the 4 years.
2. You get $X of stock grant when you join. This grant gets divided into $X/4 over the next 4 years. The number of stocks then gets decided each of those 4 years based on the value at the start of that year. So let's say you get a stock grant of $400k. So you get stock worth $100k every year. If the stock is at $1000 for the first year you get 100 stocks for the first year. If the stock goes up to $2000 at the start of second year, you get only 100 stocks. If it goes down to $500 for the third year, you get 200 stocks. So upside is capped. You will only get stocks worth $100k each year.
2. is what followed by Coinbase and Stripe. Some other companies are moving that direction as well. 1. is followed by FAAMG.