[arrow7000]

With a black hole the mass is concentrated in a much smaller location than it is in a planet. Which means you can get a hell of a lot closer to the centre of mass of the black hole, which is where you start getting the extreme gravitational forces that you would never get on a planet

[jjcon]

That distinction is pretty much a rounding error though compared to supermassive black holes - matter around a planet massed black hole is extremely unlikely to emit gamma