The insulation in a glove or mitten will help keep the heat inside.
Synthetic - Man-made materials like Thinsulate, PrimaLoft or Polartec used to keep the skin dry while remaining low in bulk.
Down - Down tends to be a little bulkier but is considered the warmest of all insulation.
Heated - Heated gloves or mittens will have a battery-operated accessory to provide consistent heat.
None - No insulation.