There are many differences. Please see below for the introduction of QSFP+ and QSFP.
QSFP+: QuadSmallForm-factorPluggablePlus. Four Small-Size Pluggable (QSFP+) solutions are designed for high-density applications. The system components include electromagnetic interference (EMI) shielding, active optical cable (AOC), passive copper cable assemblies, active copper cable assemblies, optical MTP cable assemblies, optical loopbacks, host connectors, connectors, and cage stacked integration. The documentation for SFF-8436 specifies a radio transceiver mechanical form factor with latching mechanism, host-board electrical-edge connector and interface. Hot-swappable transceivers integrate 4 transmit and receive channels 4. Molex's QSFP+ transceiver can replace 4 standard SFP+ transceivers. The result is greater port density and overall system cost savings over traditional SFP+ products. The QSFP+ cable assembly is designed to provide a very high density of stacked connector configurations. This system will support 10G Ethernet, Fibre Channel, InfiniBand*, SAS and SONET/SDH standards using different data rate options. Including InfiniBand* separate data rate (SDR), double data rate (DDR) and four data rate (report), Ethernet system (10 ~ 40gbps), Fibre Channel (8, 10gbps), SAS (12gbps).
The QSFP: QuadSmall Form-factorPluggable. Four Channel SPF Interface (QSFP). QSFP was born to meet the market demand for higher density, high-speed pluggable solutions. This 4-channel pluggable interface has a transmission rate of 40 Gbps. Many key technologies mature in XFP have been applied to this design. The QSFP can be used as a fiber optic solution with speed and density superior to the 4-channel CX4 interface. Since four channels of data can be supported at 10Gbps per channel at the same port volume of the XFP, the density of the QSFP can be 4 times that of the XFP product and 3 times that of the SFP+ product. The QSFP interface with 4 channels and higher density than the CX4 has been adopted by the InfiniBand standard.