Cannot seem to get my head around the key differences between the Blueprints and the Approval Process. For me it seems like different flavours of more or less the same thing - especially now that we have the option of Record Locking.

Have a quote to sales order process that I need our sales team to follow, and it seems obvious to use Blueprints with Record Locking as the way to go. Blueprints allow me to move the quote through a process of internal approval, emailing the client, create actions, etc., and eventually converting the quote to a sales order. With Record Locking, I believe I can now also lock to quote for changes between appoval and conversion stage.

So, here's my question:

Why would anyone embed an "Approval Process" within this flow, when nearly the same things can be achieved with mixing a Blueprint with Record Locking? What am I failing to understand?