internal - R & D department develops new technology. the impacts that this may cause, such as the retrenchment or workers, is caused by an internal influence
external - there are two forms here. technology developed by competitors may force other companies to adopt that technology in order to remain competitive. the other is if there are new compliances required by the govt that must be met, such as if new laws came into being that forced companies to change the way they conducted electronic transfers on the internet, this would be classified as an external influence. furthermore, the latter could also be classified as a legal influence.
hopefully the hypotheticals have helped!