Grid is a bottom-up framework where Grid itself only provides the basic core functionality and you build it up with the addition of modules of your choosing. Unlike its counterparts Healbot and Vuhdo which are top-down frameworks where the addon includes many features you may potentially end up disabling them. That is the key difference in the technology. These are differences in decisions made by the developers of these addons. Some prefered the all in one solution approach and others prefered building a framework where pieces can be bolted on as needed.
You want to download the addon "Grid" as that is the core. Anything else such as GridStatusHots, GridStatusRole, GridStatusRaidIcons, GridSideIndicators, and so on are additional modules for Grid which allow you to customize it with the features you want. The addon Grid2 is still not a release version so don't use that thinking its the next version, it isn't ready for widespread use. Healbot and Vuhdo have built in modules for click casting however Grid focuses on the frame only and how the information is displayed. If you want to use a click casting tool with Grid you would need another addon called Clique.
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