The 345M and the M7 are family. They are quite a bit different, the 345M is extremely budget, it is intregrated in the chipset and therefore uses shared memory. Clock speed is only 170 MHz and it has no TCL engine. The M7 is a discrete chip, has 32 MB dedicated RAM, a TCL engine and runs at 290 MHz.

Other than that, the rendering pipelines of both chips are identical and therefore there is very little difference between them on the software side.