What is the difference between efficient and effect?

Efficient is an adjective that describes something that is performing in the best possible way, or is very economical. Effect is a noun that is the result of a cause or an illusion.
Examples: 1) Her new appliances are very energy efficient. 2a) Driving for long periods of time gives John the effect of drowsiness. 2b) The special effects in the movie Avatar were amazing.