It is recommended to have the SAME vocabulary at home and school.
If the vocabulary is different it will not only confuse the child but also lead to different motor patterns due to different positions of the same vocabulary. And most importantly, we cannot restrict the child to speak certain words in school and certain words at home! If we don't expect that from the typically developing children, we cannot expect it of AAC users !
The app is the child's voice and we have to ensure that the child has access to all the vocabulary that is relevant to him, both at home and at school.