In simple terms, there are resistors used for limiting current and resistors used for cutting voltage.
Resistors in series with LED are used for limiting current. For 5V you can use 220-1K resistors and you will do fine. Lower value will give you a brighter led but also it will consume more energy. Values too low will cause your Led to fry.
As for voltage-cutting resistors, it will depend on the current requierements of the circuit, but if you are dividing 5V in half, then if the schematic uses 2 1K resistors in series you could use values close to that as long as they are the same (2 470 or 2 1.5k)
But if there are sensors or transistors involved, you should use what the schematic says unless you know well what you are doing