The terms laptop and notebook are used interchangeably to describe a portable computer in English, although in some parts of the world one or the other may be preferred.
There is some question as to the original etymology and specificity of either term—the term laptop appears to have been coined in the early 1980s to describe a mobile computer which could be used on one's lap, and to distinguish these devices from earlier, much heavier, portable computers (often called "luggables"). The term "notebook" appears to have gained currency somewhat later as manufacturers started producing even smaller portable devices, further reducing their weight and size and incorporating a display roughly the size of A4 paper; these were marketed as notebooks to distinguish them from bulkier laptops.
Regardless of the etymology, by the late 1990s, the terms were interchangeable.