1.  Meaning :the most basics or important quality of something

1.1 Situation:Use it to describe the basic rule which you find out from sth

1.2 Example ：The essence of knowledge is what you gained form Self-examination

2.1 Meaning ：liquid obtain form plant or flow,especially used in cooking

2.2 Situation：Describe some material used in cooking or cosmetics

2.3 Example： Chinese are very fond of using food essence in cooking such as ：Essence of chicken

Example2：The Facial Mask essences is made from various materials,just like rice,rose,cucumber etc.