There is military disability retirement which is not the same as VA disability. VA has two disability programs, VA pension, non service connected based on need and VA compensation, service connected not based on need.

Rules are different than SSDI. SSDI has no percentage rating - it's either yes or no. Some military retirees have part of their military pension paid out as non-taxable service-connected VA compensation based on a percentage system, and go to work full time. It's possible to qualify for both, either or neither.