You can invest up to £7 000 in a Maxi ISA.
Additionally you have the potential for much higher returns than a Cash ISA.
Normally the money is invested in a number of funds. Typically it will be a mixture of Corporate Bonds & FTSE 100 Shares.
It is something you will need advice on, an IFA should be able to help
ISA Deadline 5 April. Use your Allowance or Lose It!