QSFP28 (Quad Small Form-Factor Pluggable 28) and QSFP (Quad Small Form-Factor Pluggable) are both types of transceiver modules used for high-speed data transmission in networking equipment. The key difference between them lies in their maximum data rates.

1. QSFP (Quad Small Form-Factor Pluggable): This is an earlier version and supports data rates up to 40 Gbps. It is commonly used for 40 Gigabit Ethernet applications.

2. QSFP28 (Quad Small Form-Factor Pluggable 28): This is a newer and more advanced version, supporting data rates up to 100 Gbps. It is used for 100 Gigabit Ethernet applications.

In summary, if you are looking for higher data transmission speeds, QSFP28 would be the better choice as it supports faster rates compared to the older QSFP standard. However, the choice between QSFP and QSFP28 also depends on the specific requirements of your network and the compatibility with your existing equipment.

If your network infrastructure supports 100 Gbps or higher speeds, then QSFP28 would be the more suitable option for high-speed data transmission. Always check the specifications and requirements of your networking equipment and infrastructure before making a decision.