Quant: Paired Comparisons test

I really cannot differentiate when to use mean of differences test or differences of mean test in hypothesis testing. The wordings of every problem confuses me. Kindly Guide!

if samples are dependent use mean of differences

Right, but to expand on that - if you can take an observation from sample 1 and say “this goes with a particular observation in sample 2” use paired comparisons otherwise use differences in means.