Usability tests can be used to evaluate the usability in any stage of the development process. This study investigated the difference of how an employee in the company developing the product evaluates the usability of different prototypes compared to how external users evaluates the usability of the same prototypes. Usability tests were conducted on both low-fidelity prototypes and high-fidelity prototypes to see if there is any difference in the type of feedback. Both the low-fidelity prototype and high-fidelity prototype represented the same feature in early-stage development. The findings suggest that employees are more critical when subjectively evaluating the usability after having tested on a high-fidelity prototype compared to users regardless of what prototype they have been testing on and employees that tested on a low-fidelity prototype were comparable to external users. The findings also suggest that confusing terminology can be detected by both types of participants, and that they can suggest the same types of improvements. Employees seem to be evaluating the usability with the whole system in mind.