This is an excellent video from Knowledge Odoo on YouTube. Here is a brief overview of what is explained ...
Planned Transfer has a Demand quantity to confirm later. (Default create-form from Operations > Transfers or accessible via the kebab menu-item Planned Transfer from the Inventory dashboard.)
= Operations tab on a Transfer (stock.picking) = Reporting > Stock Moves = stock.move = planned to move
Immediate Transfer has a Done quantity right away. (Default create-form from the Inventory dashboard.)
= Detailed Operations tab on a Tranfer (stock.picking) = Reporting > Product Moves = stock.move.line = effectively moved