The AXI DMA IP is the general-purpose, high-performance IP one should use to move data between memory-mapped devices (e.g., BRAM and DDR), or between memory-mapped device and AXIS stream interfaces.
The AXI MM-to-Stream IP is a specialty IP designed to encapsulate entire AXI MM transactions and move them over an AXIS interface (e.g., between two FPGA's). It's a way to 'extend' an AXI MM interface, without requiring all of the (possibly hundreds of) IO pins.
-Joe G.
