Thanks for asking, great question. The Pinterest App and Sales Channel are the same thing! There are just two different ways to install it, either through the Sales Channel manager in your Shopify Admin, or through the Shopify App Store. Either way, this will install the same Pinterest Sales Channel.
Glad to hear you've been liking it so far! We do have a blog post on Pinterest Marketing if you're interested in learning a bit more, and are just getting started.
If you do encounter any issues with the Pinterest sales channel, it's fully supported by Pinterest. You can check out their Pinterest Help Center. Or you can always contact them via: email@example.com for any specific questions you may have.
Let me know if you have any other questions!
Hilary | Community Moderator @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog