The terms "100G QSFP" and "QSFP28" both refer to optical transceiver modules used in high-speed data communication, particularly in data centers and telecommunications networks. While they share similarities, they are not exactly the same, and the key difference lies in the data rates they support.

1. 100G QSFP:

• "100G QSFP" refers to a form factor that supports data rates of up to 100 gigabits per second (Gbps).

• This term is often used generically to describe various types of QSFP modules that can achieve 100G data rates. The modules could use different optical technologies, such as 100GBASE-SR4 (short-range) for multimode fiber or 100GBASE-LR4 (long-range) for single-mode fiber.

2. QSFP28:

• "QSFP28" specifically refers to a form factor of the QSFP (Quad Small Form-Factor Pluggable) standard that supports data rates up to 28 gigabits per second per channel.

• QSFP28 modules are designed to support 100G data rates, but the "28" in QSFP28 represents the individual lane speed of 28 Gbps. QSFP28 modules are commonly used for 100G Ethernet applications.

In summary, the main difference lies in the naming convention and the underlying technology. "100G QSFP" is a broader term that encompasses various QSFP modules supporting 100G data rates, while "QSFP28" specifically refers to the form factor designed to support 100G data rates with each channel operating at 28 Gbps. The industry has largely adopted QSFP28 as the standard form factor for 100G applications.