Panko is, in the traditional sense, breadcrumbs made using crustless Japanese bread (actually an evolution of West European bread, as bread came to Japan via Portuguese explorers and merchants) in such a way that you end up with a particular texture.
The primary differences compared to more traditional breadcrumbs are that panko produces a lighter, airier texture when used for breading, and that it tends to absorb much less fat and oil than ‘regular’ breadcrumbs.
That texture is actually really important for some dishes. Tonkatsu is probably the best example of such a dish, authentic tonkatsu has a noticeably different breading than many other methods of preparing breaded pork cutlets due to the texture and other properties of panko.
The second aspect (less absorption of fats and oils) has also made usage of panko increasingly popular in western cuisines because you can get somewhat healthier results when breading and then frying things.
For meatballs and similar things where you are largely just using the crumbs as a binder, such benefits are less clear, though you will end up with a noticeably different texture in the final product depending on whether you use panko or a different type of breadcrumbs. Based on personal experience, the closest you can get is probably with dry breadcrumbs produced using a fine grater.
As an aside, you will notice I have exclusively used ‘panko’ by itself above. This is intentional, because ‘panko’ is actually Japanese for ‘bread crumbs’, and thus saying ‘panko crumbs’ or ‘panko breadcrumbs’ is not only redundant, but linguistically incorrect.