SFP28 (Small Form-factor Pluggable 28) and QSFP28 (Quad Small Form-factor Pluggable 28) are both transceiver form factors commonly used in data networking and telecommunications equipment. The main difference between the two lies in their form factor and the number of electrical lanes used for transmitting data.

25G SFP28 ER 1310nm 30/40KM

SFP28 transceivers have a single electrical lane and are typically used for 25Gbps Ethernet and Fibre Channel connectivity. They are designed to be hot-swappable and usually used in switches, routers, and network interface cards.

QSFP28 transceivers, on the other hand, have four electrical lanes and are capable of transmitting data at up to 100Gbps. They are used for higher-speed Ethernet and Fibre Channel connections and are commonly found in high-density switches and routers, data center interconnects, and storage area networks.

In summary, the main difference between SFP28 and QSFP28 lies in their form factor and the number of electrical lanes, with QSFP28 supporting higher data rates and being used for more high-speed networking applications.