The reason we chose to use the Shopify analogy is because we power the nonprofit's frontend fundraising experience, much like an online storefront does for ecommerce. An example of this is http://donate.campwinston.com which is powered by Giveffect.
The Giveffect marketplace is the aggregator/hub whereby any client licensing our software can push their fundraising campaigns for discovery. This is just an added extension of the solution to provide clients with a venue for campaign marketing and donor acquisition.
So "Shopify for nonprofit fundraising", while limiting, would have been completely clear. But "Shopify meets Salesforce"...now that's confusing :) Trust me I know how hard it is to come up with these so definitely not trying to be negative. If your customers get "Shopify meets Salesforce" without further explanation then it's probably just me being slow :)