[TillE]

Diablo 1 is probably the only notable game you could legitimately describe as a real-time roguelike.

Diablo 2 drifts pretty far from the formula, to the extent that it largely defines the "action RPG" genre as we still know it.

[thriftwy]

Diablo 2 has hardcode mode which actually pushes it closer to roguelike than Diablo 1. I'm not sure what other differences do you have in mind.

[thaumasiotes]

I'll take your word for it; I'm not familiar with the differences between I and II.