In my experience, neeps and tatties refers to the Scottish dish of mashed turnip (neep = swede or swedish turnip, the big yellow ones usually served to cows, not the little white ones) and mashed potatoes. It is most famously served with haggis, the much-maligned "national dish" of my homeland.
In England, which is near Scotland, "bubble and squeak" (note spelling) refers to fried leftover cabbage and potatoes (optionally with onion).
Re: Bubble and squeak gaining its name from the sound of the digestive system, have you ever had rumbledethumps? This is the Scottish version of bubble and squeak, the difference being that it is baked in the oven with lots of cheese. Parp!!
Briefly trawling the Web tends to confirm me in my opinions.