Way different. The economy was fundamentally weak at the time of 9/11, but it was clearly in recovery mode by then. I think 9/11 may have delayed the recovery by a few months, but the direction of the fundamentals were "green". Had 9/11 happened a year earlier, that may have changed things.
The fundamentals of the economy today are much worse than at the time of 9/11. How much worse it will get and how much of the ultimate pain is priced in the market today remains to be seen.