It’s difficult to give a single answer. So where a 1070 might be used you may find one laptop allows it to run at close to desktop speeds while another cripples it to reduce power and heat requirements. You need to read specific reviews.
In this case, while the laptop one is slower, it's marginally so. The GTX 1070 sips power well enough that the straight-up model in laptops is just very slightly slower, by about 10-15%. The max-Q is significantly slower.