Developer Mode vs Customize Form?

I’m having a hard time understanding the difference between putting frappe into developer mode and using customize form…

Other than the fact that I can edit the default fields in Developer Mode, what’s the difference?

My understanding is that Customize Form doesn’t actually change the base doctypes or their database structure, but supplements it with additional fields and metadata. Upgrades (are supposed to) handle these customizations relatively gracefully.

If you instead alter the database structure in a doctype in Developer mode, there’s a higher chance of breaking things, especially on upgrades.