In another thread, I confused everyone by being wholly ignorant about the terms concrete vs cement vs mortar vs grout.
So how's this first pass at clarifying:
Cement --> aka "Portland cement" - it's the sticky gray glue. Lime --> aka white "hydrated lime" - prevents sand & cement separation. Sand --> mixed with cement - I think it gives strength to cement. Mortar --> cement + lime + (rough) sand (rougher mix for stone & brick) Grout --> cement + lime + (smoother) sand (finer mixture for tile) Concrete: --> cement + lime + sand + gravel (courser mixture)