There were a few posts last season about BTU's in coal. From what I remember there is a difference from area to area as well as type to type.
In general anthracite has more BTUs than Bituminous. But there are some Bituminous coals that have the same or higher BTU's than some of the poorer Anthracite coals.
Each 'batch' of coal from a particular vein of coal has it's own characteristics. Each one may have more or less ash, volitiles, and other contaminants compared to another vein of coal.
So it may have been a sales pitch, but it is based in fact. If he was 'selling' you on his coal, he should have shown you the assay on his coal. If the coal is sold to industry an assay of the coal is required.
Forum member Berlin is very knowledgable on this, maybe he will post here and correct me if I'm off base. Maybe he will educate us on this subject.
Hope this helps, Greg L