What are the differences between oil and grease?
In general terms greases are more viscous than oils, so they are thicker and a lot more gluggy and less liquid than oils. Think of the grease that goes into wheel bearings versus the oil that goes in your engine. I am not aware of grease or oil having any actual chemical definition (only fats), so there is no real true answer to this on a chemical level (that I am aware of, and there is much I do not know).
