Core bit and Drill bit

Core bit noun - A hollow drilling bit that is the cutting part of a core drill; allows core samples to be taken.

Drill bit and core bit are semantically related. In some cases you can use "Drill bit" instead a noun phrase "Core bit".

Drill bit noun - A bit used in drilling for oil.

Core bit and drill bit are semantically related. Sometimes you can replace phrase "Core bit" with "Drill bit", this phrases are similar.