Thetokos mean Mother of God.
Panagia means the Most Holy.
These two words are most used to refer to the mother of Jesus in the orthodox church.
The Mother of God has a very special place in the eastern faithful because she is the chosen one to give a human body to the Son of God, saviours of our souls.
Usually in the highest point there is a church dedicated to the Mother of God. Alternatively can be dedicated to Archangel Michael or Profitis Ilias.
In every place there is a church or more than one dedicated to Panagia that is very special to the local people.
Panagia icons have many names but are not referred to as a special patronage of someone or something in particular like in the roman latin church. The Mother of God protects everyone that has faith in her and asks for her intercession to God.
Three important names of Panagia in holy icons:
Panagia Eleousa, Mother of God of tenderness
Panagia Hodigitria, Mother of God that show the way
Panagia Platytera, Mother of God wider than the sky