cofactors, coenzymes, cosubstrates

[TinySeahorse]

There are a number of similar threads but not exactly what I'm looking for.

My biochem book breaks them down like this:
Cofactors - divided into (1)metal ions and (2) coenzymes
Then, coenzymes are further broken down into (1)cosubtrates and (2) prosthetic groups

Another source breaks them down like this:
Cofactors - (1) organic and (2) inorganic
Then, inorganic is broken down into (1) Coenzymes and (2) prosthetic groups

Which is it? I am confused.
Are prosthetic groups a type of coenzyme? Where do cosubtrates fit into here??

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[aldol16]

I wouldn't worry too much about classifications. I would worry more about understanding the general concepts and how they interconnect.

Prosthetic groups are coenzymes, if the coenzymes are tightly bound. In other words, a coenzyme is a large class of molecules and if those molecules are really tightly bound by the other enzyme, then the coenzyme is a prosthetic group. You can think of co-substrates as other molecules that have to come in and bind to the enzyme in order for the reaction to be carried out. So something like the methyl-THFs for methylating something, carried out by methyltransferase enzymes.