Catalog and Carousel Ads are a unique feature to Meta Ads that connects directly to your online store and pulls product data. Using a Catalog to create a Carousel Ad will allow you to utilize your current product photos and information as a variable ad creative. This can be useful for companies like clothing brands, who might have varying styles of different pieces available for purchase. By linking your Ad Account and Shopify (per se, could be weebly, square, etc.), you give the Meta algorithm the option of which products to show to individual customers, which could result in higher conversion. The downside to this is the limited and sometimes misformatting of your ad creative, which only really works well for certain applications (like clothing brands). Especially if you’re starting a brand from scratch, you likely want to put a bit more effort into your ad creative than porting over your product photos.