SFP (Small Form-factor Pluggable) and QSFP (Quad Small Form-factor Pluggable) are both types of transceiver modules used to connect networking equipment such as switches, routers, and network interface cards to fiber optic or copper network cables. The main differences between the two are their form factor, data transfer speeds, and the number of channels they support.

1. Form Factor:    - SFP modules are smaller in size and support a single channel for transmitting and receiving data.    - QSFP modules are larger and support multiple channels for transmitting and receiving data.

2. Data Transfer Speed:    - SFP modules typically support data transfer speeds of up to 10 Gbps per channel, although newer models can support speeds up to 25 Gbps.    - QSFP modules support higher data transfer speeds, typically ranging from 40 Gbps to 400 Gbps, depending on the specific variant.

3. Number of Channels:    - SFP modules support a single channel for transmitting and receiving data.    - QSFP modules support multiple channels, with variants supporting 4, 8, or 16 channels for transmitting and receiving data.

In summary, SFP modules are smaller and support lower data transfer speeds with a single channel, while QSFP modules are larger, support higher data transfer speeds, and can handle multiple channels for transmitting and receiving data.