[dwm] newbie question: floating vs tiled layout

What is the significance of tiled vs floating as that shown in the
icon on the statusbar for []= ><> ?
I'm puzzled because
1. each tag can have different layout yet the icon is common
to all tags.
2. take firefox as an example, the window can be dragged
or resized (turned in floating) but the layout icon does not change

-- 
regards,
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