What's the difference between a digital and grand piano?

[RandyWilliams]

Greetings all,

I want to purchase a piano for my granddaughter, Sylvia. She practices on her school piano and she's always sorry she can't practice more or at home. That's why, before I start looking for one, I would appreciate some experienced views on the subject. I've read here all sorts of benefits in favor of digital pianos. Is it very different playing on a digital piano, especially for someone who got used to playing on a grand piano? Are there any cons against them and what are they?

Thank you all
Randy