DSP Builder LUT, ROM: what's the difference?

Hello Alteraforum,

I am wondering about the difference between the LUT and the ROM block from "DSP Builder Blockset/Storage".

The only thing I can see is that the LUT block can be configured to not register the address. Apart from this, both LUT and ROM appear to be doing exactly the same, or am I missing something? Could anyone tell me a reason why I would want to use the on or the other? Thank you.