I've always thought of it as: An engineer engineers solutions, frequently from scratch or very small pieces. A developer develops solutions, often from larger pieces, focusing on implementing them to solve business needs. It's subtle but I think there is some differentiation. I think the vast majority of companies only require developers, or mostly developers, including Etsy.. because let's be honest what is Etsy doi…
Developers build specific tools using generic pieces. Think of using AWS to serve up a CMS with business-specific code hooking into a parent company's payment processor.
Engineers build general tools using specific pieces. Think of building AWS DynamoDB.
edit: It's not about LOC, it's about understanding systems and algorithms... the distinction between putting Lego blocks together, and understanding how and why those bricks were made.