CFP2 (C form-factor pluggable 2) and CFP4 (C form-factor pluggable 4) are both optical transceiver form factors used in high-speed networking applications, but they differ in terms of size, data rates, and applications. Here are the key differences between CFP2 and CFP4: 

1. Form Factor:

• CFP2: CFP2 is larger than CFP4 in terms of physical size. It is designed to support higher data rates and typically has a larger footprint.

• CFP4: CFP4 is a smaller form factor compared to CFP2, allowing for higher port density on networking equipment.

2. Data Rates:

• CFP2: CFP2 is designed to support higher data rates, often up to 100 Gbps or more. It is commonly used for 100G and 200G applications.

• CFP4: CFP4 is designed for slightly lower data rates compared to CFP2, typically up to 100 Gbps. It is commonly used for 100G applications.

3. Port Density:

• CFP2: Due to its larger size, CFP2 typically results in lower port density on networking equipment.

• CFP4: CFP4's smaller form factor allows for higher port density, making it suitable for applications where space is a critical factor.

4. Applications:

• CFP2: Commonly used in networking equipment for high-speed applications, such as 100G and 200G Ethernet.

• CFP4: Used in similar high-speed networking applications but with a focus on achieving higher port density in constrained spaces.

5. Module Types:

• CFP2: Supports a variety of optical module types, including SR (short-range), LR (long-range), and ER (extended range) modules.

• CFP4: Also supports various module types similar to CFP2 but with a smaller form factor.

6. Industry Adoption:

• CFP2: CFP2 was widely adopted in the industry for 100G and 200G applications.

• CFP4: CFP4 gained traction as a smaller alternative, offering higher port density for 100G applications.

When choosing between CFP2 and CFP4, it's essential to consider the specific requirements of the networking application, available space, and desired port density. Both form factors adhere to industry standards, ensuring interoperability between different manufacturers' devices that support the same form factor.