I think it's equal in terms of heat dissipation, for my part I removed the supplied heatsink as my motherboard has one for 2 ssd's and they are cooled by the motherboard fan and its large built-in heatsink.

I don't know about the effectiveness. I think it's the same thing. However, it's better to use the one on the motherboard, because that's how the motherboard was designed. It's more compact and design.
The heat sink that comes with it can be easily removed. There are also heat adhesive strips supplied with the motherboards.