The 125,000 mile US award is Concorde roundtrip, with ongoing service in Europe in Business Class.

If you return to a different gateway (i.e., no Concorde service) that will be in First Class.

The two cheaper awards are specifically for Concorde JFK->LHR, with no onward service included. Return, as noted, is coach/business accordingly.

Does anybody know WHY the one-way Concorde awares are eastbound only? My suspision is that business flyers (who pay their incredible fares) would rather fly overnight NYC-LHR than lose a day of business by flying Concorde (which makes daytime flights). But LHR-NYC they like the Concorde - can work in both cities (gee, what a treat), as opposed to losing the entire business day on a jet.