Effectiveness is doing things that get you closer to your goals. Being efficient is performing a task (important or not) in the most economical manner possible.
The default mode of the modern world is to put more emphasis on being efficient without regard to effectiveness.
Remember this: What you do is much more important than how you do it.
To be effective means that you do what you are suppose to do. Being efficient is focusing on how you do something. Efficiency is important, but only when it’s applied in the right manner.
Apply those two principles:
Doing something unimportant well does not make it important.
Requiring a lot of time does not make a task important.