A within-subjects design (also known as a repeated-measures design) means the ===same subjects are exposed to all conditions or treatments===. This design is beneficial for controlling for individual differences as each participant acts as their own control.
A between-subjects design (also known as an independent measures design) means different subjects are used for each condition or treatment. This requires a larger sample size but avoids issues like order effects that can affect within-subjects designs.
The research involving Johnny and Mandy robots in different dealerships appears to be a between-subjects design, as it seems that different participants encountered the robots in each condition, rather than the same participants experiencing all conditions.