If you have a powered repeater pointing into a block, the block itself is powered and powers any attached torches or adjacent powerable blocks (e.g. pistons, hoppers, glowstone lamps).
However if you have powered redstone dust pointing into the block, the block behaves differently. The block will still power attached torches or adjacent powerable blocks, but it will not power any redstone dust adjacent to the block (unless it's connected to the original redstone dust). Also, interestingly it will power a repeater coming out of the block.
So I've always wondered why is this? Is there a name for these two different concepts?