The 200 series has a smaller water reservoir. The screen will only be black and white. Please be aware of the new Keurig 2.0 Digital Rights Management system and the fact that off-label pods may not work.
The 200 series tends to be slimmer and may fit better on a counter top or table. The 400s are bulkier due to increased water capacity. Also note that some will be considered commercial machines and intended for office use.
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