It has some key differences to the H1B however:
- It is a 2 year visa (H1B is 3 year) and renewable indefinitely (typically H1Bs allow one renewal);
- The E3 by default is a multiple-entry visa;
- Renewing the visa inside the US is a huge pain. It takes months from USCIS and it's more expensive than obtaining a new visa (which can only be done outside the US);
- You don't renew your visa, you renew your status. This means if you leave the US after the visa expires but your status has been renewed you have to get a new visa anyway;
- The H1B visa requires a labor certification for the position and "proof" that you were unable to find a domestically qualified candidate. The E3 visa only requires the labor certification so has a much lower barrier to entry.