Because of the amount of space available in a laptop compared to a desktop, and the need to avoid overheating, components are usually different by their design and performance. It means that many laptop cards released before the newest generation of GPU (e.g. Pascal technology from Nvidia) are less powerful than their desktop counterpart. To signify this, GPU producers generally put an "M" after the number of the card (e.g. Nvidia GTX 970M). For instance, when looking at the system requirements needed for a game, an Nvidia GTX 970M is actually ranked lower in terms of performance than the Nvidia GTX 950: the "M" at the end of the name of your laptop graphics cards could put it under the system requirements despite the actual number being the same.
NVIDIA's new 10-series laptop GPUs don't have an "M" anymore in their name as the performance is roughly on par with the desktop version. The laptop versions, however, often have a lower clock speed, so there is a 5 to 20% performance gap with the desktop version.
Also, please note that laptops usually contain two different graphics cards: a dedicated and an integrated. For more information about how to switch from your integrated GPU towards the dedicated GPU, visit this article.
Finally, feel free to check the official websites of Nvidia and AMD for a detailed overview of their different products.