“Efficiency is doing things right; effectiveness is doing the right things.”

— Peter Drucker

People throw around these two words pretty indiscriminately in business, usually not making a distinction between them. They’re treated as interchangeable synonyms for broadly being “good” at something.

We can think about effectiveness and efficiency as two dimensions on a grid, often (but not always) in competition with one another. More focus on one means less on the other.

That Drucker quote is a pretty solid one-line distinction. But like many quotes, it’s concerned with being pithy and memorable, but not that helpful.