I play in an English ceilidh band which also sometimes plays for what we call "Social Dance" in England. They really are not the same thing at all.

Ceilidh: At the gig, caller ask for polkas/reels or jigs, and how many bars. (+ the occasional hornpipe, waltz etc.) Band chooses tunes from its repertoire and plays, usually from memory.

Social dance: Caller contacts band weeks before the gig (hopefully) with a list of dances and tunes. Maybe sends PDF of tunes, maybe quotes numbers from the Barnes book or other reference. Band makes arrangements, rehearses and plays from music. In many cases only one tune will fit each dance (especially for Playford). Learning every tune would be a nightmare.

What we English call "social dance", the Americans call "English Country Dance". What we call "English Ceilidh" has no exact equivalent in the USA, but Contra is similar (and we also have contra over here). Judging from what happens at the Cambridge Contra Club, everything is either jigs or reels and picked at random from a book of tune sets ("jigs 17", "reels 5" etc.)

We played for social dance workshops at Chippenham Folk Festival this year. One of our callers who was doing a "Zesty Playford" workshop was deliberately vague about tunes ("any 32 bar tune", or "jigs at 115 bpm") but the others were very specific about tunes for dances. There was some confusion, typically because there are sometimes two tunes with the same name, but a flurry of emails resolved things well enough by the time we had to play.

Incidentally the two dance genres are so different we don't even play the same instruments for each, keeping fiddle and recorder/flute but swapping melodeon for cello and switching the keyboard from piano to harpsichord. The baroque ensemble lineup apparently went down very well with the dancers at Chippenham, who are used to having a piano accordion leading the band.