The FESTO SMT-10-PS-KL-LED-24 is a proximity detection switch, cataloged under Limit and Proximity Switches. It's the part number you need for a direct BOM line replacement or a new build specifying this order code.
The SMT-10-PS-KL-LED-24 is a cable-type proximity switch with an LED indicator. The LED gives you a quick visual on switching state during commissioning or fault-finding — no need to break out a meter for a simple go/no-go check.