-Quartz-
A quartz watch uses a battery to send an electric current through a tiny quartz crystal, which vibrates at a precise frequency to drive the movement. It's simple, accurate, and low-maintenance — batteries typically last 12 to 15 months.
-Solar-
Solar watches work the same way, except a solar cell beneath the dial converts light into electricity, charging a rechargeable cell instead of a disposable battery. No battery changes, and many models can run for months in the dark once fully charged.
In short: both are electronic movements prized for accuracy and low upkeep — the difference is simply where the power comes from.
