Since the beginning of the spring semester, I’ve been sure to distinguish between “since” and “because” because the difference, while typically disregarded, is neither subtle nor insignificant.
Indeed, as I learned while studying for an internship program’s copy test, the words’ meanings are entirely dissimilar. “Since” should be used when one refers to elapsed time: Since I studied for the copy test, I have begun using these words correctly. “Because” is used for for explanations: I use these words correctly because I discovered the difference while studying for the copy test.
Simple enough.
Because you now understand the distinction, you can use the words correctly as well, even if you’ve used them interchangeably since you started speaking.