It does depend where you live and how your parents referred to these meals. When two people coming from different backgrounds get together, adjustments and agreements or disagreements result.
To me, I mean the following when I refer to the terms in the list.
Dinner = A meal in the evening typically comprising of meat, potatoes and two veg
Tea = A meal in the evening comprising of sandwiches, cake and or scones and a pot of tea
Lunch = A meal in the middle of the day typically comprising of meat, potatoes and two veg, or a sandwich type meal.
Supper = something before you go to bed.
Somebody in the thread referred to a butty with or without a top slice of bread, I've not come across this before, I've always thought a butty is a complete sandwich.
Generally, I love the various ways we refer to our food around the country, it's part of what makes us different and is particularly interesting when it involves regional dishes.