When we were on Skye in Scotland, a Ceilidh was defined as more than two people gathering for stories, song and perhaps "a cup of tea and wee dram".

Here in Maine (and elsewhere in the US) the sessions I have been to are generally in a public place and the focus is instrumental music, also called a "jam". In my experience, a ceilidh tends more to a convivial gathering with food, song, story and dancing added, often in a private home.

If you are in Maine, let me know and we'll have one at oor wee "ceilidh palace"
cheers- Julia