Maybe for you it is practically the same as a green card, but for others there are still meaningful differences:
1. Can't go into business full-time with your own company, without taking a big risk with the green card.
2. Can't make major career moves like changing from engineer to manager, because of the "same or similar job" limitation.
3. Re-entering the country with Advance Parole means you'll be sent to the back room for possible interrogation, where anything could happen.
4. Can't renew your driver's license on the spot (this depends on which state you live in). When you go for renewal, they take away the original license and give you a temporary driving permit which cannot be used as ID and is unlikely to be accepted by car rental companies (this is a problem for me because I sometimes travel to one of my company's offices far away and need to rent a car). Then only after some number of weeks when they verify your status you get the renewed license ... and it is only valid for one year then you'll have to repeat the same crap again.
5. And most importantly: If you lose your job and your employer revokes your I-140 before you can find another "same or similar" job, your I-485 is denied and you have to leave the country.
EAD is more like a portable H-1 than a green card. Your every move is still at the mercy of the government and your employer.