Jam is always made from the whole or cut fruits, cooked to a pulp with sugar, producing a thick, fruity, spread. Jam is lathered onto toast, fresh scones or used as a base for tarts such as a Bakewell.
Jam, when made correctly and potted into sterile jars, will keep for up to a year, as the quantity of sugar in the jam in the cooking helps in the preserving (keeping) qualities.
Jelly is made using only the juice of the fruit and sugar. It should be bright and sparkling when finished. It is a slightly more complicated method as the fruit, once cooked needs to be strained slowly overnight through a muslin cloth or jelly bag. This juice once collected, then is cooked with sugar to produce the lovely clear jelly. Any over handling or squeezing of the fruit pulp can make the jelly cloudy though it will still look good, isn't as pretty.
Jelly can be used the same way as jam on toast and scones, but not as a base in tarts; it melts very quickly. Another good use for jelly is to sweeten and gloss up a sauce or gravy. Redcurrant is the one most often used. Quince and Rowan's jelly make good partners for game and cheese.
Marmalade is similar to jam but made only from bitter Seville oranges from Spain or Portugal. The name of Marmalade originates from the Portuguese Marmelos, which is a quince paste similar in texture to an orange spread.
Marmalade is eaten most often for breakfast on toast and also used in some recipes like duck and sponge puddings.
Lemon Curd, also known as Lemon Cheese, is made with lemons, eggs and butter. It differs from jam or jelly as it contains less sugar and must be eaten within weeks of making so is not classed as a traditional preserve.https://www.thespruceeats.com/difference-betwee...