to keep it all simple, not all displays are the same, each is unique, some are warmer than others, some cooler, some brighter, some darker. These differences are very little when it comes to a single product typically though, especially when it’s a high quality high build product.
No two displays have the same amount of light they let out though; if it is as bright as it is, then chances are its either lost brightness over the years, or it just doesn’t produce as much light as your laptop.
chances are the latter is true; laptop displays are typically brighter for obvious reasons, but newer displays can be just as bright, but chances are since your model is older it has lost some brightness to it, or it just plain didn’t have it in the first place. Only way to fix it is adapt the laptop making it darker.