Let´s start with the similarities:

- Both "ser" and "estar" mean "to be" and both are irregular.
- Both are used as the main verb in a sentence.
- Both are auxiliary verbs. "Ser" is used in the passive voice, and "estar" is the   auxiliary of progressive (-ing) forms.
- Both require agreement with other elements of the sentence.

Now let´s contrast the verbs:
- "Ser" is used to describe a permanent state, and "estar" usually refers to a    temporary condition.
  - Yo soy Juan. (I am Juan.)
  - Yo estoy enfermo. (I am sick.)
  - El agua del mar es azul. (Sea water is blue.)
  - El agua está caliente. (The water is hot.)

- When "ser" is followed by an adjective it describes an inherent quality or   characteristic, whereas "estar" describes a temporary -transient- quality which is    the result of a change.
 - La manzana está madura. (The apple is ripe.)
 - Esa manzana es dulce. (That apple is sweet.)
 - Javier está enfermo. (Javier is sick.)
 - Javier es enfermo. (Javier is (permanently) sick.)

  Note how adjectives change their meaning according to whether they are used with "ser" or "estar".