Is a plan chest the same thing as a flat-file cabinet?

The two terms refer to the same type of product — wide, shallow-drawer storage for oversized flat documents. "Plan chest" is more common in UK and art/woodworking contexts; "flat-file cabinet" or "map cabinet" is the standard commercial term in North America. Either way, you're looking at the same basic product. FindOfficeFurniture.com uses "flat-file cabinet" as the standard term and carries commercial-grade options in both steel and wood — call 888-719-4960.