How does heat transferred inside Earth differ from the way heat is transferred from the sun to Earth

The sun transfers heat by infrared rays. Heat in the Earth is transferred by contact with hot rocks or lava. Please remember that nobody has gone inside the Earth more than a small fraction of a mile, so everything we think we know is only an educated guess.
en.wikipedia.org/wiki/Kola_Superdeep_Borehole
www.google.com/search?q=deepest+mine+shaft