Answer:
The difference in temperature is significant means that the lower-boiling liquid finishes distilling at a temperature that is too low for the higher-boiling liquid to be in vapor form yet.
Explanation:
The temperature will rise as the vapor of lower-boiling liquid rushes into the distillation head. However once the lower-boiling liquid is done distilling, there is a temperature drop because while the lower temperature liquid is done distilling, the temperature is still too low for the higher-boiling liquid to be rushing in as a vapour, so the temperature drops.