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.)

The napkin math factor I use is to get the average power you need to divide solar and wind's name plate power by about 4. So to get the same amount of total yearly energy as a 1GW nuke plant that runs 24/7 you need 4GW of solar. Because solar produces about 6 hours of power per 24 hour day.

From a capital cost perspective this is not nice at all. Too be fair upside of solar/wind is solar and wind farms don't go down for a year and a half of unplanned maintenance like nuke plants sometimes do.