Effectively is the adverb of effective (adjective). It means doing something in a way which produces the expected result. You achieved what you wanted. Efficiently is the adverb of efficient. It means doing something in the best possible way, with minimum waste and effort. You achieve something with little waste or effort.

Hi Chili! Being "effective" is all about doing the right things. For example, choosing the right tasks to do in a certain circumstance, choosing the best method of selling something for example. "Efficiency" is all about doing something right, doing things in the quickest and most time-efficient way, and getting the best response in doing so. Essentially, these words can be interchangeable, but if you're looking for the distinction, this is it! Hope this is helpful!