Dell Inspiron 7000 series or 5000 series

Hello everyone,, I'm looking to buy a new laptop. 15". I'm interested in the Inspiron 7000 series and 5000 series from 2018. They don't seem that vastly different. They even have the same specs in certain configurations. Does anyone have experience with them? I believe 5000 has a plastic chassis and 7000 has a metal chassis, but performance wise, is it worth the difference in $$$? Your feedback is great appreciated!!!!!