Collection / category
A named group of products browsed as one page: 'New in', 'Under $50', 'Shoes'. The sections your shop is organised into.
See it
What it is
A named bucket of products that shoppers browse as one page: 'New in', 'Under $50', 'Running shoes'. Two flavors exist. A manual collection is a hand-picked list you drag into order. An automated (or 'smart') collection is a rule: everything tagged 'linen' under $80 that is in stock. Rules scale, hand-picking merchandises.
Category and collection get used interchangeably by most platforms, and plenty of them ship only one of the two words. Where the split does exist, it is taxonomy versus merchandising. A category expresses structure: the nav tree, the breadcrumb, the shape the catalog is classified into, and a product can sit in several categories at once. A collection expresses curation or a rule: 'Gifts for dads', 'Sale', 'Best sellers'. Check what your platform actually means before you argue about the words.
Gotcha: collection pages are usually your biggest organic landing pages, so their sort order and their copy matter more than the homepage. Default sort is often alphabetical or newest, which quietly buries your best sellers and floats sold-out items to the top. Set an explicit order, and push out-of-stock products to the end.
Ask AI for it
Build a collection page for an online store. Top: a compact hero with the collection title, one line of merchandising copy, and the product count. Below: a responsive product grid (2 columns mobile, 4 desktop) with image, title, price, and a sold-out badge, plus a sort dropdown ('Featured', 'Newest', 'Price low to high') that updates a URL query param so the view is shareable. Push out-of-stock items to the end of the default 'Featured' order and paginate at 24 products with a 'Load more' button that keeps scroll position.