Hi @averyfreeman ,
I have no personal experience with either laptop but given the top cover assembly (Item #2 in the parts list as shown in the maintenance and service guide) into which the touchpad fits also has different part numbers even between the 15K and 17K models which share the same description i.e. country specification and backlit keyboard, a 15K touchpad may not even physically fit properly into a 17K top cover assembly.
Usually manufacturers don’t assign different part numbers for no good reason whereas they can and do use the same part across different models, so there most probably is a difference, but maybe just not discernible to the eye. For example there could be wiring differences in the touchpad circuit or connection to the motherboard.
It may be that they’re interchangeable but perhaps it is better sticking with the correct part number rather than risk causing damage to either the motherboard or the touchpad by installing the incorrect part just on the off chance that they are. Just my view.
If you search online by using the part number only there are a few suppliers but maybe they’re not suitable for you.
Here are two suppliers with stock: supplier 1, supplier 2