Why did the same powers seem to act so completely differently between people?

Prue's Astral projection worked completely differently than Rex's. Hers was more like a physical clone while Rex's was actually more spiritual and he could give mental suggestions.

Zach and Christy's telepathy was different from Rainers Orr that demon that was after Bane. Zach and Christy seemed to only be able to give and receive thoughts and sense while being able to tap. Into others powers. The demons could read thoughts and give thoughts but they also did mental suggestions

For some reason when Piper was turned into a warlock with prues wedding her power completely changed to actual freezing but anyone else who's stolen her power just got it as it is.

Just a few examples