What this sensor is and what matters for fit
This Omron E2B-M30KS15-WP-C1 2M is a shielded inductive proximity switch with a 30 mm diameter cylindrical brass housing and a 15 mm sensing distance. It's a normally open, NPN sinking output sensor with a 2 meter PVC cable. The shielded construction means you can mount it flush in metal without the target getting detected through the side — that's the big difference vs. an unshielded model. For a machine builder or MRO planner, the 15 mm range is solid for detecting ferrous targets like cam followers or bolt heads on moving assemblies.
The E2B-M30KS15-WP-B2 2M is the same mechanical package — same shielded 30 mm barrel, 15 mm sensing, same 2 m PVC cable — but it uses PNP output and is normally closed. That means if your BOM calls for an NPN NO sensor like this C1, dropping in the B2 would require swapping the output polarity and the logic sense. No mechanical issue, but the wiring won't work without a re-pull. If you've got a PNP NC system, then the B2 is the match; otherwise this C1 is the correct part.