512K versus 128K. Eight way as opposed to two way cache sectoring, and yes, a higher FSB, 400 vs 533. I have the same chip and it's great. I got mine to 2.90GHz with a 685MHz FSB completely stable (P95 for 18HRS+), paired with 2x256 Dual Channel PC4000 DDR @ 446MHz CAS 2.5-3-2-5. This system is absolutely smoking. You should try to OC it some time. Even if you don't, a 2.26 is one helluva lot faster than a 2GHz Celeron.
The P4 architecture relies on a large cache owing to it's long pipeline. With the small cache of the Celeron, a mis-predicted branch can mean a pipeline stall, which kills performance. A 2.8GHz Celeron is about the same performance as an 1800+ Athlon if I remember that article correctly.