Ummm...These are both good options actually.
The main difference is that Wordpress is a universal open-source content management system that can be useful for any business. On the contrary, Shopify is a web-based ecommerce solution created specifically for retail. Also, Wordpress is cheaper. You can start your journey at $0 if you go with their free option, whereas Shopify offers you a $30 startpack. The main point is that an ecommerce shop will work perfectly fine on both. It's just a matter of taste.
By the way, here's a succint overview of all ecommerce platforms if you need a more in-depth look.