QSFP+ (Quad Small Form-factor Pluggable Plus) and QSFP28 (Quad Small Form-factor Pluggable 28) are both types of transceiver modules used in high-speed data communication applications, particularly in data centers and high-performance computing environments. The primary difference between them lies in the maximum data rate they support:

1. QSFP+:

• Data Rate: Supports data rates up to 40 gigabits per second (Gbps).

• Applications: Commonly used for 40 Gigabit Ethernet (40GbE) connections and InfiniBand applications.

2. QSFP28:

• Data Rate: Supports data rates up to 100 gigabits per second (Gbps).

• Applications: Primarily used for 100 Gigabit Ethernet (100GbE) connections and InfiniBand applications at higher speeds.

In summary, the main difference between QSFP+ and QSFP28 is the maximum data rate they can achieve, with QSFP+ supporting up to 40Gbps and QSFP28 supporting up to 100Gbps. As technology evolves and higher data rates are required for network infrastructure, newer standards like QSFP28 are introduced to meet these demands. When selecting a transceiver module, it's essential to choose the one that aligns with the data rate requirements of the specific network equipment and applications in use.