In Portugal, "marmalade" was made of quince, period. The other things were probably called jellies or jams.
I've come full circle on it, as you can buy the original Portuguese marmalade in Canada now.
https://www.realcanadiansuperstore.ca/quince-jam/p/20159955_...
The Portuguese word for 'quince' is 'marmelo,' which is where the word marmalade comes from.
For instance, in Italian _legally_ "marmellata" should be applied only to citrus preserves, but in common usage it came to be used to refer to every kind of jam (the correct term being "confettura", which is rarely used).
In German if I recall correctly "Marmelade" just means "jam".
The fruit is very bitter, and this gives the marmalade a wonderful wake-you-up sharpness.
By the way, the word marmalade brings memories of my English teacher at school telling us how the three "a" in that word were pronounced each one in a different way.
However, my mum made it once, and I still remember it fondly, it was warm and syrupy and sticky and tasty, and it was perfect.
But we never made it again, it's such a god damn hassle.
Same with Ketchup, we made it a couple of times and it was amazing, but man, do these things take a lot of time and fiddling. Much easier to just buy off the shelf.
As my mother grows old and our generation has less time for dishes that take more than ~2 hours, I feel some of the charm has been leaving. We don't buy marmalade now, even though it's readily available.
I don't think it is. I've lost count of the number of times I've asked for marmalade to go with my toast and been told sorry we don't have any.
I have some Marmalade, but used it once about 2 years ago.
Marmelada has a texture similar to a grainy pate and it is very sweet.