The differences between dedicated RAM block and MLAB memory

I read something about these two kinds of memory block. I compare dedicated RAM block to Xilinx's Block RAM and MLAB memory to Xilinx's ditribute RAM, although the latter analogy is barely satisfactory.

Do I think right?

I feel there may be some subtle differencs between dedicated RAM block and MLAB memory. What are these differences?

I need to use RAM memory in my design. Which one should I use?

Thanks in advance~