I know we’ve had threads on this over the years, but “supper” and “dinner” are the same thing for me, and that is the evening meal. Eating either at 6PM would be more or less normal for Americans, especially with kids, but my preferred time is 7:30 - 8:00.
Actually, we’d normally just use “dinner” and only rarely use “supper”. But when the word “supper” was used, it was understood to be exactly the same as “dinner”.
“Dinner” has historically been a term to refer to the main meal of the day.
In a more agrarian society when the midday meal was normally the main meal, the meals were breakfast, dinner, and supper. But for the vast majority of families in the U.S., for many decades now, the evening meal has been the main meal of the day on normal occasions. Hence breakfast, lunch, and dinner have long been the normal terms for the three meals of the day.
The more archaic usage leaks through for many of us at Thanksgiving and Christmas, when we call the day’s big meal ‘dinner’ regardless of what time of day we eat it. ETA. And when the the big holiday meal is early enough that there is an evening meal in addition to the big holiday meal, it’s called ‘supper’ because the term ‘dinner’ has already been used for the earlier, bigger meal.
We didn’t have a choice this year. Because of various commitments the whole family didn’t get together until 6 pm Thursday today. We might start dinner around 7.