Trying to understand the use cases for block grids and block lists

Well with block lists you can basically do just about anything that doesnt require a template and an url You could build your own page with it. Have a header and a footer and a center area that consists of only a blocklist editor In the blocklist editor oyu define blocks, for example, a TextBlock, a ImageBlock, a QuoteBlock etc. Now the client can build up their own page using the blocks. Or you could use it for some menu that needs icons and a url. You can define a block that consists of a IconPicker and a Url Picker, now you can add links with an icon to the blocklist, easy! But it's always a list of items. Grid however, does the same, but it has grid functionality, so you can define columns / rows / areas, and define per layout which blocks are allowed. You could configure it like a pagebuilder, or just a helpful tool for placing content in multiple blocks. (This is just the basic functionality, you can even add settings per block, add templates per block, and more, highly recommend the docs https://docs.umbraco.com/umbraco-cms/fundamentals/backoffice/property-editors/built-in-umbraco-property-editors/block-editor)

okay thanks

Generally I use them as their names suggest: block list for vertical or horizontal lists (they can wrap) block grid for rows and columns. Also block list pairs nicely with CSS Flexbox and Block Grid with CSS Grid. Also you can nest and mix and match. I have used block list in block grid in Umbootstrap FAQs example