I have a 1994 Explosif
(see here for some notes on it) and a 1995 Kilauea, and I would say they are noticeably different.
I would agree that the Kilauea is an excellent frame, and indeed there’s very little difference in quality - both are made from Tange Prestige heat-treated tubesets. Whether you say the Explosif is 'better' depends on whether its characteristics are ones you value - if not, you might prefer the Kilauea.
The tubeset designs are quite different. The Tange Prestige Concept tubes on the Kilauea are notable for having the same top and down tube, whereas the Explosif is a more modern design with a much stronger down tube and a lighter top tube. This makes the Explosif the stiffer of the two and the more suitable for racing, whereas the Kilauea is slightly softer. The Explosif is c100g lighter overall, even though its top and down tubes are slightly heavier. So although the description does suggest that they share the same stays, I wonder whether in fact the Explosif has lighter stays, as it has to make that weight difference somewhere.
I must admit that I have only ridden the Kilauea with a rigid fork and I have only ridden the Explosif with suspension, so this could be affecting my judgment of each frame. Nevertheless, my impression is that the Explosif is slightly more sophisticated (although not equal to the 96 Columbus Max Explosif in that respect) and feels slightly faster, with its stiff front end and the rear end feeling slightly better controlled. Nevertheless the Kilauea is a fun cross-country bike, and with the P2s you overtake modern bikes up hills so easily you have to smile.
I would strongly recommend either frame.
