A company is a “limited company” if the liability of its members is limited by its constitution. It may be limited by shares or limited by guarantee.If their liability is limited to the amount, if any, unpaid on the shares held by them, the company is “limited by shares”.If their liability is limited to such amount as the members undertake to contribute to the assets of the company in the event of its being wound up, the company is “limited by guarantee”.
Source: gov.uk