"Explicit memory involves recalling previously learned information that requires conscious effort to receive" for example personal experience ("x happened to me on y day") and factual information you had to learn ("city is the capital of y country")
"Implicit memory is unconscious and effortless" for example muscle memory (how to ride a bike etc), understanding categories (knowing what things are), having emotional associations with things (you react emotionally in certain ways to certain things) .
Lots to think about here, for example explicit memory of things that fall in my special interest is stronger than things that don't.
Constant earworms seem related to implicit (short term auditory) memory.
Also the differences in encoding the different forms of memory vs retrieving them.
eg I have vivid visual memory but have difficulty recognising people.