What's the difference between a Yamaha grand piano GC1 and C1?

These two models are both the same size but come from two different categories from Yamaha. The C1 is from their Conservatory Classic Collection while the GC1 is from the Classic Collection, a lesser quality instrument.

The GC1 has only a bass sustain pedal while the C1 has a Sostenuto pedal. The C1 has a soft close and locking fallboard and nicer lid prop arrangement.

What is appropriate for your needs depends on a number of things, among them your level of expertise and your budget. I would go and play them both, or better more than one of each, and also compare them to other instruments.

I use a Yamaha.
I suggest you have a look at YAMAHAPKCLUB.
It will have everything your looking for.

Yamaha C1 Piano

the piano does not need a super coach john