With Sky Sport, you can watch up to 2 different sport programmes, simultaneously using the same account.
Example : You can watch the match A from one device and the match B from another device but not the match A from 2 different devices.
For Sky Show and Sky Store, you can watch 2 or 4 video streams at the same time on different devices, depending on the subscription you selected.
In order to simplify the usage of multiple devices, you may connect up to 4 different devices with your Sky account, and you may modify these connected devices anytime in "My Account".
For more information: What happens if my account is already connected to 4 devices?