One of the two was a trademark leading to the other one being pushed as an alternative. But I can't even remember which one -- at this point I couldn't even tell you which phrase is more widely used.
EDIT: IIRC at some point "Notebook" was used to refer to laptops that were smaller and/or lighter than the regular (rather heavy and bulky) laptops at the time. There's also a major online discounter called notebooksbilliger.de (literally "cheaper notebooks"). In day to day language I would err towards "Laptop" being the more widespread term but not by much.
[1] https://en.wikipedia.org/wiki/Laptop#Possible_effect_on_fert...
Your comment made me think about that. Wonder how the usage in daily language changed... Maybe because notebook was English. Not sure.
https://www.google.com/trends/explore#q=laptop%2C%20notebook
https://books.google.com/ngrams/graph?content=laptop+compute...