Welcome to Anthracite David. Gets confusing doesn't it? I can't help you with the furnace models. Things are a little slow here in the summer apparently. I did a lot of research last winter before buying my coal stove. The problems with the heat and area ratings are many. The same Stove or furnace will put out varying amounts of heat depending on coal quality draft settings, and operator skill. Of course a home's heating requirements vary by a lot more factors than square footage. There are cubic footage, insulation value, air infiltration, climate, stove or furnace location for heat distribution, etc.
I think stove manufacturers vary from being overly optomistic about how much space their stoves will heat, to being cautious not to disapoint the customer by selling him a stove that is too small.
In northern NY, ( down to -20*F most winters )I need about 50K BTU to heat 1,200 sq. ft. of floor space in an older house with insulation, but not up to modern standards.
The depth and bredth of knowledge here is tremendous. Be patient and someone will probably be able to give you very good advice about the furnaces in question. Good luck.