Well, as the IIci was a very expensive, high-end machine, and as the IIsi was designed and marketed as a low cost, consumer machine, the IIci should well and truly be a better one. If I am not mistaken, the price differential between the two was something like three thousand dollars.

Mind you, it can be hard to tell the difference these days, given that we mostly only ever switch them on for a few minutes, rather than use them for hours and days at a stretch. Run a IIsi in System 6 with period software for a few minutes and it still seems plenty fast to a tinkerer, esp. with the IIsi Nubus adapter installed, which has on-board cache as well as an FPU slot.