For the glycosidic bond in maltose, why is the glycosidic bond formed between hydroxyl group on C1 in 1 glucose molecule and hydroxyl group on C4 of the other glucose molecule? Why not between, say, hydroxyl group of C2 on one and hydroxyl group of C4 on the other?
In a cyclic molecule of glucose, C1 is the result of the aldehide group linked to C5. This makes C1 a reducing carbon that can share electrons. This is why C1 must always take part in a glycosidic bond.
The other carbon may be C'1, C'2, C'4 etc. That changes the structure and name of the molecule (i.e. two glucoses bound by α 1-4 bond is Maltose and by α 1-6 is Isomaltose)