Which type of hypothesis employs the terms 'significant difference'?

The correct choice is that both directional and non-directional hypotheses employ the term 'significant difference.'

In hypothesis testing within research, both types of hypotheses are used to make predictions about the outcomes of an experiment. A directional hypothesis specifically predicts the direction of the expected relationship or difference between groups, implying that there will be a significant difference in a specific direction (for example, one group will score higher than another). On the other hand, a non-directional hypothesis suggests that there will be a significant difference, but does not specify the direction of that difference; it merely states that something will differ between the groups without indicating how.

Both types aim to determine whether the observed data supports a significant difference, often assessed using statistical tests that evaluate the probability of the observed results occurring under the null hypothesis, which posits no effect or difference. Therefore, both the directional and non-directional hypotheses are fundamentally concerned with identifying whether there is a statistically significant difference present in the data.