Big difference my friend!
They both do the same job, except when it comes to disassembling. although with clearing mine I came to the conclusion that the grey silicone has a lower melting degree (Melted Cheese) as for the black silicone the whole housing will deform before the black silicone would even be phased by the high temp. (Black sealant simply becomes hot and that's it!)
It took me forever but am fairly decent with mods and tool's, It can be done but be careful.... since the black silicone wont even begin to melt your housing will be able to flex. While the housing with the tabs is flexible I took a Flat Head screwdriver and ripped out the silicone it gets all jacked up by doing this!.,.,.,. when all apart I re heated it and re shaped the seal, (only the black part) Yes a Major Pain!
I used regular white bathroom caulk.,., Hey its all I had laying around...lol
I could touch it up with a sharpie but Im not that anal about it.
It can be done but I strongly don't advise it for someone with little patience as I almost snapped mine in two.