Can somebody explain the difference between this two bone options when I Alt+P?

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“Disconnect bone” seems to do nothing, going to pose mode, selecting and moving the feet that was disconnected VS moving the one that didn’t get disconnected seems to make NO visual differences.

While the first option literally DISCONNECT the bone from the main bone structure [seems like this should be really called disconnect bone instead of the second option that seems to do nothing ?]

Can somebody explain this ? Thanks.

Future Bracer reading this, just choose “Clear Parent”, this is what is needed for IK.

Clear Parent is as it says. Disconnect Bone is when the head of the bone is disconnected from the tail of the previous bone.