Acoustic nylon string guitars, the string pressure is lower, the strings are wider – possible less pain on fingers. Finally it is personal choice. I personally like the sound quality of the nylon strings too.
We can’t change steel strings to nylon on the same guitar – width differences etc.
Students usually get the Yamaha C4o or similar when they want a nylon string guitar.
Electric steel string will not work with nylon strings, since Nylon strings will not work with the usual electric guitar pickups. They require metal strings to vibrate in the pickups electromagnetic field to produce electric output.
Nylon string electric guitar will need piezzo pickup.
Playing slide music on electric steel strings are easier since they have sustain and slightly different construction since they are not constrained by the need to produce resonance.