LSTMs are very different. Think of it this way. LSTMs store information about the current problem you're solving. DNCs store information about the world.
LSTMs are designed to capture long range dependencies, e.g., "this word at the start of the sentence interacts with this word at the end of the sentence."
DNCs are designed to incorporate outside information, e.g., "i happen to know (from background knowledge) that these two people in this sentence are married"
LSTMs are designed to capture long range dependencies, e.g., "this word at the start of the sentence interacts with this word at the end of the sentence."
DNCs are designed to incorporate outside information, e.g., "i happen to know (from background knowledge) that these two people in this sentence are married"