Custom Segments in 2015.2

I was playing around with the new custom segments feature, although admittedly not super in depth. However, what are the main differences between custom records and custom segments at this point? It didn't look like custom segments appeared in the main filter for Reports (ie, where you can choose Dept, Class, Loc, Period, etc to be across the top of the page). It also doesn't look like you can use them when customizing financial statements where you can choose different 'group by' segments, (ie: Dept, Class, Loc, Customer/Project, Item, Account).

So if these things just show up like regular fields on forms and in reports/saved searches as criteria and filters, what benefit do they have over custom fields/records? The only difference I'm seeing is that you can make custom segments hierarchical (which is definitely great) and having baked in limitations on which Dept, Class, Loc, Sub that they can be matched up with. Am I missing something?