Capacity is the most they can produce at any given time. Solar only produces power during the day. Geothermal produces power 24 hours a day, without any regard for day or night. Therefore for the same “capacity” geothermal will produce more power per day because it produces for more hours a day at the same rate.
(This does not account for any complications such as the cost of that capacity or whether geothermal has other downtime to consider.)
(This does not account for any complications such as the cost of that capacity or whether geothermal has other downtime to consider.)