What is the difference between a Grant of Probate and Letters of Administration?

A Grant of Probate is issued where the deceased left a valid will with named executors who are willing and able to act. Letters of Administration are issued where there is no valid will, or where the named executors cannot or will not act. Both documents authorise the holder to deal with the deceased’s estate. The key difference is the basis on which they are obtained and, in intestate cases, who is entitled to apply.