I have a feeling you may wantto replace some of them.
First, identify what they all are, and write on them, every metre or so. Rub the metal with detergent and a green scourer, and wipe dry, first, then a felt pen or Stabilo marker will work. The reason for marking every metre is that you might, later, misidentify a pipe after glancing at a distant mark.
The central heating pipes you can identify by turning on the heating for a bit. The pipes that heat up before the radiator are CH Flow, and the ones that heat up after the radiator are CH return.
The hot-water pipes will heat up after you run the hot tap.
The mains supply pipe will be the coldest, and will get colder after you run any tap.
The tank fed cold, if any, will get a bit colder after you run a cold tap, but not as cold as the mains.
The gas pipe will be slightly below room temperature, but will not change much.
The pipes from the boiler to the cylinder will be primary flow (heats up first) and primary return (heats slower, and not so hot). They may be big pipes.
Then identify what they are made of, with a magnet and your green scourer. Copper-coloured are copper. Attracted to a magnet are iron (they may be rusty internally). Grey and nom-magnetic are lead (if you have lead pipes on the supply or cold tap, ask your water company to test your drinking water for lead content. They need changing and there might be a subsidy or other assistance.
Have you got a hot-water cylinder? What colour?