How is "disability" defined?
Individual policies commonly use one of two definitions of "disability".
One definition is that you are unable to perform your own occupation ("own-occ" policies) – the job you were doing before disability or illness. A variation on this theme is the modified "own occupation" policy that covers you for your own occupation so long as you are not gainfully employed elsewhere.
The second definition, much less attractive to the purchaser, defines disability in terms of your inability to perform any occupation for which you are suited by education and experience.
The distinctive between the major forms can be critically important. For example, if a surgeon loses a hand, s/he may not be able to do surgery. If s/he has an "own occupation" policy, s/he would be able to recover, even though she was able to work as a doctor in a non-surgical field. With the inability to perform any occupation, there would be no recovery, even if the surgeon could only be a tour guide.