Yes. When you learn to play the piano you are training your nervous system to respond to the sensitivity of the piano.
Real pianos respond to the way you touch it. If you press a key with more weight in your arm you will get a bigger sound. If you press a key with less weight you will get a smaller sound.
There is a direct connection between what you feel in your body when you play and the sound that comes out of the piano. Not only does this make the piano so rewarding, but it also engages students over the long-term.
Keyboards that plug into a wall have limited or no capacity to do this. You can learn all the theory and analysis on a keyboard, however, the most fun part of the piano, its sensitivity to your touch, is lacking.
If you only have a keyboard, go ahead and start lessons while you actively look for a piano. What you learn in your lessons will help you evaluate and select a good piano.
