Hi @Seller_sOT4Fkr4E70mQ, at a very simplified level Send to Amazon is you sending a product directly to FBA whereas AGL is an Amazon service where you can ship ocean cargo from China directly to the Amazon fulfillment network in the US, UK, and EU from your manufacturer.

For more details, I recommend reviewing Intro to Send to Amazon on Seller University and the Amazon Global Logistics program page.

Topher