What is the b75 chipset and what is the difference bewteen other chipsets?
well, to quote anandtech:
As with the latest CPUs, the newer B75 chipset has brought out of the box Ivy Bridge CPU support to less expensive motherboards, filling out the Panther Point platform. Ian thoroughly covered the Z77 chipset and compared it with H77. The B75 chipset is similar to Z77 and H77 with a few important differences for midrange buyers: two fewer USB 2.0 ports (eight vs. ten), one less SATA III port (one vs. two), and support for neither Intel RST (firmware RAID) nor SRT (SSD caching). PCIe 3.0 and 2.0 configurations are the same on B75 as they are on H77. The important point is that B75 enables less expensive motherboards that lack features that might not be important to midrange system builders, allowing money to spent on faster CPUs, GPUs, better SSDs, etc.
Essentially, the B75 chipset is a budget intel chipset, which supports the ivy bridge architecture natively. B75 motherboards will have less features, but they will be cheaper, and the missing features might be unimportant to mid-range builders.