Gas distributors manage networks which distribute gas to businesses and homes. Electricity distributors manage the network of cables that supply electricity. There are several different gas and electricity distributors in the UK. And there’s also the Meter Point Administration Service which creates and maintains meter point administration numbers (MPANs) for electricity meters.
You might need to contact your distributor if you have a problem with your supply (find out who your distributor is). Remember that they can’t help you with questions about your bill - you’ll need to talk to your energy supplier about this.