Design is a job which requires creativity and innovation. No appliance we use today could've been made without the brilliance of designers in the first place. Engineers are tasked with using scientific principles to make the device operational.This is the key difference between engineers and designers. You can cite the example of architects and civil engineers in the same tone as well.
While architects create a design of a given building, engineers have to make sure whether the design is viable and how will facilities such as electric cables and water supply be incorporated into the design. Furthermore engineers also have to analyze geological factors to ascertain whether the design would impact the safety of the inhabitants.