Note: This is just a re-worded version of question 329036, and we have had reports of both different wordings being seen in (different) exams recently. Please let us know if you see this in the exam, thank you!
Learning Objective 032.04.01.10.04: Describe why data from an EFB can differ from data derived from RTOM tables or similar.

EFB (Electronic Flight Bag) means any portable electronic device for use by the flight crew, which may be a laptop, a tablet or an integrated device within the flight deck. Many EFBs include commercial navigation packages, enabling the whole flight to be planned and executed on the same device. It may also hold charts and AFMs and are widely used in an effort to reduce the amount of paper flying around a cockpit.

It is very common to use software on the EFB to make performance calculations, as the software is easier to use, more accurate, and much faster than manually going through the paper charts and tables.

The reason the EFB produced performance figures may be slightly different from those from the charts are mostly down to accuracy. When using paper charts and tables, interpolation has to be done, and the charts can sometimes be difficult to follow with high accuracy, so they are then made with slightly conservative figures, and the operator is not able to interpret them to the same accuracy as the EFB software can interpret its own data, creating slight inconsistencies between the two sources.