Store and catalog are two interchangeably used terms to refer to a shopping website, but there are substantial differences between both.
In the digital world both catalog and store, are presented through a website or app. Both of these are your gateway to introduce your offering to your customers. Let's explore what are the key differences and where each of them is relevant
Yes, a well-presented digital catalog helps as great marketing and sales channel for you. Customers will research online and buy offline.
Yes, you will still benefit a lot from having a rich catalog. Your consumers do research, seek more info, try to gauge the brand, most of this outside the marketplace. Your own branded website which has a catalog that presents your products in your own style, presentation, and language (well beyond the generic style which a marketplace does) helps your customers make that buying decision.
You may not need a store (checkout) if you are staying away from the fulfillment which marketplaces do extremely well these days (of course at non-trivial fees). You can direct the consumers to the marketplaces from your website when they try to buy.
High-value product sales need way more convincing than commodities, and hence an independent catalog is really important.