1. Product Generation / Design Revision: The core difference indicated by “02C” vs. “04C” in the part numbers typically signifies an internal design iteration or version update within the product family. The LCE04 likely incorporates updated internal construction, material processes, or manufacturing standards aimed at improving performance consistency, mechanical endurance, or compliance with newer certification norms, while maintaining identical basic electrical specifications and form-factor interfaces. 2. Series Segmentation Implied by Part Numbering: The descriptor variation “N12” vs. “N4X” likely points to different sub-series or application categories within the same broad product family. This usually indicates distinctions in non-critical performance parameters, such as mechanical life (number of operations), electrical life, internal arc quenching system design, or applicable safety standard/certification revisions. As the newer model, the LCE04 may feature optimizations or adjustments in these areas. In summary, the two devices are fully compatible in core electrical parameters and mounting dimensions, allowing for direct substitution. The differences lie in the internal design and product revision, with the LCE04, as the updated version, theoretically offering equivalent or superior reliability. For critical applications, it is advisable to consult the manufacturer's latest technical documentation or contact Siemens directly to confirm whether their performance is fully equivalent under specific demanding conditions (e.g., high-frequency operation, shock/vibration environments).