Difference b/w effective testing and efficient testing ?

Efficient means performing or functioning in the best possible manner with the least waste of time and effort; having and using requisite knowledge, skill, and industry; competent.
Efficient testing will be testing which uncover most of the bugs in less effort and time.

Testing Efficiency = (No. of defects Resolved / Total No. of Defects Submitted)* 100

Effective means obviously whether we are getting the bug, whether there is any benefit of the testing or not. Effective testing is whether we are getting the bug or we are just wasting our time.

Test Effectiveness = Loss due to problems / Total resources processed by the system