Wabi stands for sadness, desolation and loneliness, but from poetry the word has eventually been transformed into something that represents simplicity, the lack of materialism and humility.
Sabi stands for "the bloom of time" - the beauty or serenity that comes with age, when wear or a visible repair emphasizes the life and transience of an object. Sabi is the rusting, the authenticity, the proof that nothing is forever and the fact that beauty is fleeting.